THE PRINCIPLES OF Astronomy and Navigation:

OR,

A Clear, Short, yet Full Explanation, of all Circles of the Celestial, and Ter­restrial Globes, and of their Uses, being the whole Doctrine of the Sphere, and Hypotheses to the Phenomena of the Primum Mobile.

To which is Added

A Discovery of the Secrets of Nature, which are found in the Mercurial-Weather-Glass, &c.

AS ALSO

A New Proposal for Buoying up a Ship of any Burden from the Bottom of the Sea.

By GEORGE SINCLAR, sometime Professor of Philosophy in the Colledge of GLASGOW.

Edinburgh, Printed by the Heir of Andrew Anderson, Printer to His most Sccred Majesty, Anno d [...]

Academiae Cantabrigiensis Liber.

To the Right Honourable MAGNUS PRINCE, Lord Provost;

Alexander Brand, Alexander Simpson, Iohn Morray, and William Montgo­mery, Baillies; Iames Nicolson Dean of Gild, Edward Marjorebanks The­saurer; and remanent Members of the Honourable Senate, of the Antient City of Edinburgh. May it please your Lordship, and the Honourable Senate,

IT is neither Ambition, nor Ignorance of your Worth and Merit, which have inclin'd me, to prefix your Names to the Frontispiece of this mean Pamphlet, but the sure experience I have of your encouraging all vertuous Actions and Learning. What I have now in Equity and Reason presented, I hum­bly desire the Honourable Senate, may accept favourably. I owe all I have, [Page] and my Self too, to your Devotion and Service. I chuse rather to be doing somewhat Amiss, than doing Nothing. 'Tis the Widows Mite, which I have shelter'd under the Wings of your Pro­tection. If I should endeavour, but to recapitulat, what Sentiments of your Kindness I have found, both Time, and my Memory would fail me. None can think, that there is any Deserving in me, which can be proportionable to those unvaluable Acts of your Bounty. If there be any, I am confident, it is too too scanty to Oblige. When I was able to do more, none were found more willing. I endeavoured indeed, accor­ding to my Capacity, to contribute my Assistance for promoving that great and noble Design, which was accomplish'd; for which the Generations to come, shall call you Happy, whom you have En­riched, with Refreshing-Streams of Cooling-Waters, more Advantagious and Useful to the City, than the Fruit of the Vine. I cannot satisfie all the Obli­gations to Duty, which ly upon me. The [Page] more I was inclin'd to offer this Trifle, the more I was overcome with Reasons perswading to the contrary. But the uprightness of my Intention, to beau­tify this trivial Subject, with the Splen­dor, and Glory of your Names, will excuse the faillings of my Understand­ing. I cannot remunerat the Kindness of the Honourable Senate, better, than by Hearty Prayer, that the LORD may give you, the Spirit of Wisdom, and Government, to Manage the Weighty Affairs of the City, and His Conduct, not only to Guide each one of you, in his particular Calling, but all of you, to the endless Fruition of Immortal Life. This I fervently wish, while I am

Your Lordships and the Councils, much Obliged Servant, GEORGE SINCLAR.

TO THE READER.

I Iudge it altogether needless to Preface any thing by way of Commendation to the following Tracts. They will (I hope) commend themselves, to the intelli­gent Reader. There is first, The Doctrine of the Sphere, so compendiously set down, that nothing can either be Added, or Sub­tracted. It is the very Rudiments of Astro­nomy and Navigation, and of many other Mathematical Sciences. By the use of the Globes, the whole Doctrine of the Sphere may be easily comprehended, even by the meanest Capacity. The second Tract, is not so evident, because more Physical, and less Mathematical, but perhaps as sure. I have set down my own Thoughts only, If any Man shall offer to salve the Phenomena better, I shall be glad. The third Tract is, a new Invention for Buoy­ing up of Ships from the Ground of the [Page] Sea. This Proposal was made some few Years ago, to try the Invention and Wit of some Notional Men, but though they have plowed with my Heifer, yet were they not able, to find out my Riddle: Nay some of them were so confident to aver, that when this Proposal was made to them, How to make a Vessel Sail below the Water; they Replyed, it might be easily resolved by their Analyticks.

ERRATA.

IN the second Tract, Page 28. line 13. for earthly read earthy. pag. 33. lin. ult. for Idaea read Idea.

THE PRINCIPLES OF As …

THE PRINCIPLES OF Astronomy and Navigation.

CHAP. I. Of the Circles of the Sphere in general.

THE material Sphere, is an Instrument, where­by all the Phenomena of the Primum Mobile, are most easily known.

It is composed of Ten Circles chiefly, which are, the Equinoctial, the Zodiack, the two Colures, the Horizon, the Me­ridian, [Page 2] the two Tropicks, and the two Polars.

Those Circles, are three manner of ways distinguished among themselves. First, Some of them are called Circuli Maximi, the Greatest Circles; others are called Circuli Minores, the lesser Cir­cles. The Greatest are, the Equinoctial, the Zodiak, the two Colures, the Ho­rizon, and the Meridian; because there cannot be greater Circles in the Sphere, than they are.

The lesser Circles are, the two Tro­picks, and the two Polars. They are so called, because there are found in the Sphere greater ones.

Secondly, The Circles of the Mate­rial Sphere, while the Primum Mobile is turning about, are either Parallel one to another, Right, or Oblique, that is, to ly crosly. The Parallel Circles, are the two Polars, the two Tropicks, and the Equinoctial, which ly middle be­tween them, together with their Equi­noctial, who live under the Poles. The Oblique Circles are, the Zodiack, and [Page 3] the Oblique Horizon. For this cutteth the Equinoctial, at Oblique Angles; the other by reason of its Situation doth the same to the rest of the Circles. The Circles called Right Circles, are the two Colures, the Meridian, and the Right Horizon, because they cut the Equi­noctial at Right Angles.

Thirdly, The Circles of the Sphere, are either Moveable, or Immoveable. The Moveable Circles, are these which are turned about with the Sphere, be­ing eight in number, to wit, the Equi­noctial, the Zodiack, the Equinoctial Colure, the Solstice Colure, the Tro­pick of Cancer, the Tropick of Capricorn, the Polar Artick, and the Polar Antar­tick. The Circles Immoveable, are the Meridian, and the Horizon; so called, because while the Sphere is carried about, they stand stedfast, and unmove­able.

CHAP. II. Of the Equinoctial.

THe Equinoctial, is one of the greatest Circles, of the Sphere Moveable, and equally distant from the Poles of the World. It is called one of the greatest, that it may be distinguish­ed from the lesser, as well from those, which are fixed in the Sphere, as from others, which we must imagine to be in it. It is called Movable, that it may be distinguished, from the Horizon of those, who live under the Poles, which coinciding with the Equinoctial, must differ from it in this, that the one is Movable, the other Immovable. Last­ly, by reason of the third difference (equally distant from the Poles of the Sphere) it is distinguished from the Oblique, and Right Circles of the Sphere.

It is called by divers Names. For [Page 5] sometimes it is called the Equator, sometimes the Equinoctial, and some­times the Middle, and greatest of the Parallels.

The Uses and Offices of the Equino­ctial are these. 1. It measureth the first Motion. For this Circle, of all the Cir­cles of the Sphere, under any Position whatsoever, moveth equally; and there­fore, it ought to be also the Measure of Time, it being most fit for deter­mining the quantity of the Artificial, and Natural Days. For this cause, it is, that the Degrees of the Equinoctial, are called by some, Tempora, Times. 2. It pointeth forth to us in the Eclip­tick, the two Equinoctial Points; those Points, in which the Equinoctial, and Ecliptick cut one another, in the be­ginning of Aries and Libra. For when the Sun cometh to these Points, the Day and the Night are of equal length over all the Earth, which falleth out on the 10 or 11 of March, and on the 13 or 14 of September. 3. That which is Anomolous, and Irregular in the Ob­lique [Page 6] Motion of the Zodiack, is re­duced to a sure Rule, by the help of the Equinoctial. 4. It divideth the Sphere into two equal parts; the one called the North part, in which is the Pole, named Polus Septentrionalis, Bo­reus, or Articus: the other called the South part, in which is the Pole, nam­ed Polus Australis, Meridionalis, or An­tarticus. 5. By this means, it divideth the Zodiack into six Signs, called Nor­thern Signs, and into other six called Southern Signs. 6. From the Equino­ctial are numbred the Declinations of all, and whatsoever Points in Heaven, as well South as North. The Declina­tion of any Point, or Star, is an Arch of a Circle of Declination, measured between the Equinoctial, and the said Point, or Center of the said Star. Cir­cles of Declinations, are of the Greatest Circles in the Sphere Movable, passing thorow the Poles of the World, and any point given. 7. Upon the Equino­ctial, we reckon the Right Ascension of any, or whatsoever Point in Heaven. [Page 7] Right Ascension, is nothing else, but an Arch of the Equinoctial, measured between the first Point of Aries, and that Circle of Declination, which passes thorow the point given. 8. Upon the same Equinoctial, we measure the Ob­lique Ascension, and Descension of any point in Heaven whatsoever. Oblique Ascension, is an Arch of the Equino­ctial, measured between the first Point of Aries, and that Point of the Equi­noctial, which riseth in the same Mo­ment of Time, with the Point given. Oblique Descension, is an Arch of the Equinoctial measured between the Point foresaid, and that Point of the Equino­ctial, which sets in the same Moment of Time, with the Point given. 9. Upon the Equinoctial, we count and reckon the Ascensional Difference, which is no­thing else, but an Arch of the Equino­ctial, by which Right Ascension differs from Oblique. 10. Upon the Equino­ctial, we measure the Rising and Setting Amplitude. This Rising and Setting Amplitude, is nothing else, but an Arch [Page 8] of the Horizon, measured between the Rising, or Setting of the Equinoctial, and the Rising or Setting of any Star, or Point given. 11. Upon the Equi­noctial, we number the Longitudes of Places, and upon the same, we reckon the Latitudes of Places. The Longitude of a place, is an Arch of the Equinoctial, measured between the first Meridian, and the Meridian of the Place. The Latitude of a Place, is an Arch of the Meridian measured between the Equi­noctial, and Zenith of the Place. 12. The Equinoctial is most useful for making of Sun-Dials: for there must be as many Hours upon the Plain, as there are 15 Degrees in the Equinoctial, four and twenty times numbred.

CHAP. III. Of the Zodiack.

THe Zodiack, is one of the Great­est Circles of the Sphere, Mov­able, [Page 9] under which the Planets perpetu­ally haunt.

The first and second Difference are added, as in the Definition of the Equi­noctial. The third, which is in these words (under which the Planets per­petually haunt) do distinguish the Zo­diack from all other Circles. For it may come to pass, that, this or that Planet, by his proper motion, may be under the Meridian, may be under some Horary Circle, may touch lightly the Horizon, but that is not always, nor do they always abide in the same Situation: but their stay is perpetual under the Zodiack. And because the Planets wander in the Heavens, viâ obliquâ, therefore this Circle is made oblique, and seing in this obliquity, they make digression, from this side, to that side, and from that to this, therefore Astro­nomers have granted to this Circle Lati­tude, whereby also it may be differenced from all other Circles, none of which ever claimed Latitude.

The Zodiack is divided, first in rela­tion [Page 10] to its Latitude, into North Lati­tude, and South Latitude. North La­titude, is that half part of the Zodiack, which from the Ecliptick (the middle Line of it) declines toward the North. South Latitude is opposite to this. Each one of them contains Eight Degrees, whereof the Equinoctial contains 360.

The Ecliptick, or middle Line of the Zodiack, is one of the Greatest Circles of the Sphere, Moveable, under which, the Sun from West to East moves per­petually. This Line, as likewise the Zodiack, is divided according to Lon­gitude into twelve Parts, which are cal­led in Greek [...]. Every one of these twelve, are subdivided in­to 30 parts, so that the whole Zodiack contains 360 Degrees. These twelve Divisions are called Aries, Taurus, Ge­mini, Cancer, Leo, Virgo, Libra, Scor­pius, Sagittarius, Cap [...]s, Aquarius, Pisces. But seing there are four Cardi­nal Points, two of the Equinoctial, and two Solstice Points, it hath pleased Astronome [...], to make the beginning of [Page 11] their reckoning, from the Vernal Equi­noctial Point; because the Sun being there, he not only begins the Spring, but openeth the Earth, and giveth life to all Vegetables, and things which grow; which cannot be done, either in any of the Solstices, or when he is in the Autumnal Equinoctial Point. Next, the distinction of the Signs is manifold. For some of them are called Northern Signs, and others are called Southern. The Northern, decline from the Equinoctial towards the North, which are Aries, Taurus, Gemini, Can­cer, Leo, Virgo. The Southern decline from the Equinoctial towards the South, which are Libra, Scorpius, Sagittarius, Capricornus, Aquarius, Pisces.

Secondly, Some of them are called, Signs Ascending, others are called Signs Descending. The first sort, are these, wherein the Sun, and the rest of the Planets do ascend from the South to­wards our Zenith, which are Capricornus, Aquarius, Pisces, Aries, Taurus, Gemini. The Descending are these, wherein the [Page 12] Sun, and the rest of the Planets, do move from our Zenith towards the South, which are Cancer, Leo, Virgo, Libra, Scorpius, Sagittarius.

Thirdly, The Signs of the Zodiack, are either Vernal, Estival, Autumnal, or Hybernal. The Vernal, are Aries, Taurus, Gemini. The Estival, are Cancer, Leo, Virgo. Autumnal, are Libra, Scorpius, Sagittarius. And the Hiber­nal, are Capricornus, Aquarius, Pisces.

Fourthly, The Signs are either Car­dinal, Middle, or Fixed, or Common, or Two-bodied. The Cardinal Signs, are Aries, Cancer, Libra, Capricornus: so called, because their beginnings are the very Cardinal Points. The Middle or Fixed Signs, are Taurus, Leo, Scor­pius, Aquarius. They are called Mid­dle or Fixed, because they keep the Middle place between the Cardinal and Common Signs. They are Fixed, be­cause when the Sun is in them, we have a perfect temperament of the Air, agree­ing to the given Quadrant of the Hea­vens. As when the Sun is in Taurus, [Page 13] we have a perfect Spring; in Leo, a perfect Summer; in Scorpius, a perfect Harvest; and in Aquarius, we have a perfect Winter. They are called Common, or Two▪ bodied, as Gemini, Virgo, Sagittarius, and Pisces; because each one of them, hath two Bodies in­deed. For Gemini are two Twins. Virgo hath an Ear of Corn in her Hand. Sagittarius is made up of a Man, and a Horse. And lastly, The Fishes are double. They are called Common, be­cause Astrologers find, that they parti­cipate of the Nature, both of the Fixed Signs, and the Cardinal which follow.

Fifthly, The Signs are divided into four Triplicities, which are called by Astrologers Trigons. The first is called the Fiery Trigon, which contains Aries, Leo, and Sagittarius. The second is the Earthy, which contains, Taurus, Virgo, and Capricorn. The third is the Aerial, which contains, Gemini, Libra, and Aquarius. The fourth is the Watery, which contains, Cancer, Scorpius, and Pisces.

[Page 14]If it happen, that Saturn, and Iupi­ter be in Conjunction this year in Leo, their next Conjunction will happen 20 years after, or truly 19 years, 315 days, and 19 hours, after in Sagittarius. From Sagittarius to Aries, from Aries to Leo, and so in round till 198 years and 236 days passing, they make a Transit into a new Trigon; so that the Revolution of one Trigon, consumes almost 200 year.

The uses of the Zodiack and Eclip­tick are these. 1. As the Equinoctial, is the Measure of the Pri [...] Mobile, so is the Zodiack and Ecliptick, the Square and Rule of the second Mov­ables. For as the Sun is always, in or under the Ecliptick; so are the rest of the Planets always, in or under the Zo­diack. Therefore as in the Celestial Globe, the Zodiack hath the chief place, so in the Terrestrial Globe the Equi­noctial. 2. Upon the Ecliptick we reckon the Longitude of Stars, and from the same Ecliptick, we count their La­titude. The Longitude of a Star, is an [Page 15] Arch of the Ecliptick, measured between [...]e true Equinoctial Point, or begin­ [...]ing of Aries, and the Circle of Lati­ [...]de passing thorow the Center of that [...]tar. Circles of Latitude, are great Movable Circles, passing thorow the Poles of the Ecliptick, and the Center [...]f the Star given. They are of that [...]umber of Circles, which cannot be [...]aced Artificially in the Sphere. Ne­ [...]ertheless, of that same Number, is the [...]olurus Solstitiorum fixed in the Sphere. The Latitude of a Star, is an Arch of a Circle of Latitude, measured between [...]he Ecliptick, and the Center of the [...]tar. 3. According to the Degrees, and [...]arts of the Zodiack and Ecliptick, the whole Heavens, and the whole Universe [...] divided into twelve Signs; nay eve­ [...]y Point contain'd in the Sphere of the Fixed Stars, is said to be in this or that Sign; tho, to be in a Sign, is said many ways. For first, To be in a Sign, is nothing else, but to be under any [...]welfth part of the Zodiack. In this [...]ense, the Sun is said to [...]e in a Sign, [Page 16] because he is always under the Eclip­tick. Then the Stars are said to be in a Sign, which are indeed out of the Ecliptick, nevertheless are under the Zodiack. In this sense, the Planets, which wander from the Ecliptick, are said to be in the Sign of Aries, and Tau­rus, &c. Thirdly, Any thing is said to be in a Sign, which is included, in any of the twelve parts, which arise from the division of the whole Heavens, passing thorow the beginnings of the Dodekatemoria, or the Poles of the E­cliptick; they being six great Circles, which mutually cut one another, in the same Poles. In this sense, any Star, as well fixed, as wandring, or new ap­pearing, as a Comet, are said to be in the Sign of Aries, Taurus, &c. 4. The obliquity of the Ecliptick, is the cause of the inequality of days: for seing it moves unequally, and not evenly, the Sun, which is the true Parent of Time, must of necessity make the days unequal. 5. The Year, the Month, and the four Seasons of the Year, are determined by [Page 17] the Ecliptick. 6. When the Sun and Moon, are both of them in the Eclip­tick, of necessity there must be Eclipses; and for this cause, it is called the E­cliptick. 7. How much is the obliqui­ty of the Ecliptick, so much is the di­stance, between the Poles of the World, and the Poles of the Ecliptick: so much also is the distance, between the Equi­noctial, and either of the Tropicks.

CHAP. IV. Of the Colures.

THe Colures are nothing else, but Circles of Declination, defined above, in the second Chapter of the E­quinoctial. They are called Colures from two Greek words, Kolos, or Kolo­bos, Mancus, maimed or defective, and Oura, Cauda, a Tail, because in an ob­lique Sphere, they have some part un­seen, as if they were maimed, or want­ting. But all the rest of the Circles of [Page 18] the Sphere, while it is going about, may be seen: but the Colures, have al­ways some of their parts towards either of the two Poles, lying hid, and un­seen. There are only two of them, which use to be placed in the Sphere, one whereof is called the Solstice Co­lure, the other the Equinoctial Colure. The Equinoctial Colure, is one of the greatest Circles of the Sphere, Movable, passing thorow the Poles of the Sphere, and the Equinoctial Points, the first of Aries, and the first of Libra, which are called Cardinal. By the word mov­able, the Colures are differenced; First, From the Meridian; Secondly, From the Right Horizon; And thirdly, From the Horary Circles, with all which, by one turning about of the Sphere, they are twice united. But in this they dif­fer, that those do not move, but these follow the motion of the Primum Mo­bile. The Solstice Colure, is one of the greatest Circles of the Sphere, mov­able, drawn thorow the Poles of the Sphere, and the two Solstice Points, by [Page 19] which difference, they are distinguish­ed from other Colures.

The uses of all the Colures in com­mon are these. First, We reckon up­on them, the Declinations of all the Points of the Heavens whatsoever. 2. They terminate and bound the Right Ascensions. 3. They are like unto a Right Horizon, and a Meridian in any Sphere, whether Right, Oblique, or Parallel.

The Uses of the Colures, which are set down in the Sphere, are these in common, 1. Without them, the Paral­lel Circles in the Material Sphere can­not stand, 2. By their mutual cutting one another, they shew the Poles of the Sphere. 3. They divide the Ecliptick into four Quadrants.

The peculiar Uses of the Equinoctial Colure are these. 1. It demonstrats to us the Equinoctial Points, by its mutual Section, with the Ecliptick; in which Points when the Sun is existing, there is an Universal Equinox over the whole Earth. 2. It is divides the Ecliptick [Page 20] into two halfs, the one called the North part, the other the South part. 3. It distinguishes the Signs, in which when the Sun is existing, the Days are longer than the Nights, from those Signs, in which when the Sun is existing, the Nights are longer than the Days.

The proper Uses of the Solstice Co­lure are, 1. It demonstrats to us the two Solstice Points, in which when the Sun is existing, he is either nearest to our Zenith, or furthest removed from it. 2. Upon this Colure, we reckon the Suns greatest Declination, or the greatest Obliquity of the Ecliptick, which is found to be this day twenty three De­grees, and thirty Minuts. 3. It divides the Zodiack into two halfs; the one called Ascending, the other Descending. 4. It distinguisheth the Signs, in which when the Sun is existing, the Days be­come longer, and the Nights become shorter, from those Signs, in which when the Sun is existing, the Nights become longer, and the Days become shorter. 5. In this Circle, are the two [Page 21] Poles of the Ecliptick, as many Degrees, distant from the Poles of the World, as the greatest obliquity of the Ecliptick contains. 6. Upon this Colure, the Latitudes of the Zones are determined. For between the Tropicks, is contained the breadth of the Torrid Zone, be­tween the Tropicks, and the nearest Polar Circles, are contained the two Temperate Zones, and the other two remaining Arches of this Circle, con­tain the breadth of the two Frigid, or Cold Zones.

CHAP. V. Of the Horizon.

THe Horizon, is one of the greatest Circles of the Sphere, Immov­able, and equally distant from the Ver­tical Point. It is called Immovable, that it may be differenced from the rest of the Movable Circles; but especially, First, From their Equinoctial, who live under [Page 22] the Poles. Secondly, From their Eclip­tick, whose Zenith is placed in the Po­lar Circles: for their Ecliptick every day is twice united with their Horizon, but without delay. Thirdly, From their Circles of Declination, or their Colures, who live under the Line: for there, the forementioned Circles, and the Horizon, are twice, by every Re­volution of the Sphere, united: but the Circles of Declination follow the Motion of the Primum Mobile, but the Horizon stands Immovable. The Ho­rizon is said indeed to be Immovable, but not Unchangable, for there are as many Horizons, as there are Vertical Points; and while we change our Ver­tical Point, of necessity we change our Horizon also.

Two ways is the Horizon divided. First, In relation to the Equinoctial, which is called a Right Horizon, an Oblique Horizon, and a Parallel Hori­zon. The Right Horizon, is so called, because it cuts the Equinoctial at Right Angles. It is called Oblique, because [Page 23] it cuts the Equinoctial at Oblique An­gles. And it is called a Parallel Hori­zon, when it lies Parallel to the Plain of the Equinoctial, or rather when it is united, with the Equinoctial. And according to this Relation, it hath to the Equinoctial, the Sphere it self, hath obtained the same Division.

Secondly, The Horizon is either Ra­tional, or Sensible. The Rational Ho­rizon, is defi [...]ed above, and is under­stood to divide the whole World, or Sphere of the World into two equal parts, the first whereof is called the uppermost Hemisphere, the second the nethermost Hemisphere. It is called Rational, because tho we cannot see the whole World, or the exact half of it, yet Reason tell us, by the Rising and Setting of the Sun, Moon, and Stars, that the inferior part of the World, is equal to the superior part. The Sen­sible Horizon, is nothing else, but so much of the Earth, as a man, by turn­ing his eye once, doth behold round about him.

[Page 24]The Uses of the Horizon are these. First, it divides that part of the Hea­vens, which is seen, from the other which is not seen, the Superior part from the Inferior part. 2. Thorow the Poles of the Horizon the Meridian ought to pass: therefore the Description of the Meridians depend from the Horizon. 3. By the Situation of the Horizon, we know whether it be a Right Sphere▪ Ob­lique Sphere, or a Parallel Sphere. 4. In the Horizon, the Rising or Set­ting of the Stars are observed 5. The Horizon sheweth, what Degree of the Ecliptick, what part also of the Equi­noctial, or what Degree, with any gi­ven point of the Heaven riseth or set­teth. 6. It boundeth and terminats the Ascensional Difference. 7. Upon the Horizon is numbred, the Rising or Setting Amplitude, of any point in the Heaven. 8. It demonstrats, and shew­eth the Cause and Reason of the equa­lity of Days and Nights in a Right Sphere, and of the unequality of the same in an Oblique Sphere. For the [Page 25] Horizon in a Right Sphere cutteth all the Circles of the Natural Day equally, but unequally in an Oblique Sphere. 9. From the Horizon we number the Morning-Twilight: for when the Sun [...]s distant, in some Vertical Circle 18 or 19 Degreees from the Horizon, so that [...]rom that Moment, he approach nearer [...]nd nearer unto it, then begins the Mor­ning-Twilight. But the Evening-Twi­light ends, when the Sun after his Set­ [...]ing comes to that 18 or 19 Degree [...]oresaid; for then doth the Light turn [...]nto Darkness. 10. From the Horizon, we number the Elevation of the Pole, [...]nd Equinoctial. 11. From the Hori­ [...]on are numbred various and divers [...]inds of Hours, as the Italick, and Iewish Nocturnal Hours from the West part of the Horizon: but the Babylonish Hours, [...]nd the Iewish unequal Diurnal Hours, [...]rom the East part.

CHAP. VI. Of the Meridian.

THe Meridian is one of the greatest Circles in the Sphere, passing thorow the Poles of the World, and the Poles of the Horizon. By the words, thorow the Poles of the Horizon, it is distinguished from the Horary Cir­cles, of which none but it self, passes thorow the Poles of the Horizon. It has acquired divers and sundry Names, by reason of its manifold uses, by Astro­logers, which are not fit to repeat now. What was said above concerning the Colures, and Circles of Declination, to wit, that they are in number equal to the Vertical Points, the same may be said of the Meridian, for as many of them may be imagined, as there are Vertical Points, which are infinite, pro­viding a man travel from East to West: for if a man go from North to South, [Page 27] or from South to North, he travels round about the World, without variation of his Meridian. The Brasen Meridian in the Celestial, or Terrestrial Globe, sup­plyes the office of them all, which are innumerable. But in Geographical Ta­bles, and Mapps, Geographers use to extend one Meridian, thorow two, and two opposite Degrees of the Equinoctial, for finding out, the more easily the La­titudes of Places. Of all these Meridians there is a common beginning se [...]led in the Fortunate, or Canary Islands, be­cause the Antient Geographers deemed those Islands to be the Westmost part of the World, and therefore they fixed their first March-stone there, whence they begin to reckon. But the later Geographers, have removed this March­stone 10 Degrees more Westerly, and have made the common beginning of the Meridian to pass thorow one of the Islands called Osores, whence they be­gin to reckon from West to East, imi­ta [...]ing the order of the 12 Signs.

The uses of the Meridian are these, [Page 28] 1. It distinguisheth the Eastern part, of the World, from the Western part, the Anterior part, from the Posterior part. 2. It lets us know the South part of the World, and the North part. For when the Sun is in the Meridian, [...]en is Mid-day, and when the Sun is in the Northern part, of the Meridian, then is Mid-night. 3. It divides the Nocturnal and Diurnal Time into two halfs: that is, when the Sun is come to the Meridian in our Hemisphere, as much of the day is past, as what is to come: and when the Sun is come to the Northern part of the Meridian, as much of the Night is past, as what is to come. 4. The Meridian supplies in every Oblique Sphere the place of the Right Horizon: therefore, as the Stars do ascend above the Right Horizon, so they pass over the Meridian, and those [...]ransitions are called the Right Ascen­sions of the Middle Heaven. 5. From the Meridian, Astronomers begin their Time. 6. In the Meridian, we find out the Zenith; therefore when the [Page 29] Stars come to it, they are either high­est above the Horizon, and are said by Astrologers to culminate, or they are in the lowest, and opposite part of it, which is the Nadir. 7. In the Meri­dian, we find out the distances between the Tropicks, and the whole Obliquity of the Ecliptick. 8. Upon the Meri­dian, we number the Latitude of Places upon the Earth, and likewise the Ele­vation of the Pole, and Equinoctial. The Elevation of the Pole, is defined, an Arch of the Meridian, measured be­tween the Horizon, and the apparent Pole of the World, which may be found out, after the following manner. Ob­serve the greatest and least Altitude of any of the Stars, which do not set. Subtract the least Altitude from the greatest, and divide the difference. This difference being subtracted from the greatest Elevation, or added to the least, gives the true height of the Pole. December 17. 1669, I observed with a large Quadrant, half 9 a Clock at night, the foremost Guard-star, when it was [Page 30] in the Meridian, and lowest, to have 41 Degrees, 22 Minuts of Altitude. And on Ianuary 7. 1670, at 7 a Clock in the Morning, I found it, when it was in the Meridian, and heighest, to have 70 Degrees, 27 Minuts. I subtract 41 Degrees, 22 Minuts, from 70 Degrees, 27 Minuts, and the difference is 29 De­grees, 5 Minuts. Divide this, and you have 14 Degrees, 32 Minuts, and 30 Seconds. This being added to 41 De­grees, 22 Minuts, gives you 55 De­grees, 54 Minuts, 30 Seconds. Or subtract 14 Degrees, 32 Minuts, and 30 Seconds, from 70 Degrees, 27 Minuts, and there remains 55 Degrees, 54 Mi­nuts, and 30 Seconds, for our height of the Pole at Edinburgh. 9. The Me­ridians do terminate, and bound the Longitudes of Places, as well in the Terrestrial Globe, as in the Mapps, and Cards projected in Plano. 10. The Meridians do terminate, and bound the Breadths and Latitudes of the Zones, and also of the Climats. 11. We find out in the Meridian, the Antipodes, the Anteci, and Perieci.

CHAP. VII. Of the Tropicks.

THe Tropicks are lesser Movable Circles of the Sphere, described from the Solsticial Points, by the mo­ [...]ion of the Primum Mobile. They are called Lesser, because there are in the Sphere Greater Circles, than they are. They are called Movable, that they may be distinguished chiefly, from the Paral­ [...]els of their Horizon (called Almican­ [...]ars), who live under the Poles; and [...]rom the antient Polars of those, who [...]ive under the Polars, with whom the Tropicks are equal to those Circles, which comprehend the Stars, which ne­ver come above the Horizon, nor ever go under it.

They are two in number, to wit, the Tropick of Cancer, and the Tropick of Capricorn. The Tropick of Cancer, is a lesser movable Circle, described from [Page 32] the Summer-Solstitial-Point of the Eclip­tick, by the motion of the Primum Mo­bile. The Tropick of Capricorn, is lesser movable Circle, described fro [...] the Winter-Solstitial-Point of the Eclip­tick, by the motion of the Primum Mo­bile.

The uses of the Tropicks are these 1. They demonstrate to us, in the E­cliptick, the two Tropical or Solstic Points, to wit, the beginning of Can­cer, and the beginning of Capricorn 2. They terminate and bound, the Sun greatest Declination, and consequently the greatest Obliquity of the Ecliptick 3. When the Sun comes to either of th [...] two Tropicks, he is either nearest t [...] our Vertical-Point, or furthest removed from it. 4. In an Oblique Sphere, they ly Parallel to the longest, and shortes [...] Day. 5. Between the Tropicks, i [...] comprehended the Torrid Zone, as well in the Heavens, as in the Earth: and by the same Tropicks, the Torrid Zone is divided from the Temperate Zones.

CHAP. VIII. Of the Polars.

THe Polars are lesser Circles of the Sphere, movable, described from the Poles of the Ecliptick, by the mo­tion of the Primum Mobile. For this cause, they are called the Polar Circles. They are two in number, the Polar Artick, and the Polar Antartick. The Polar Artick is a lesser Circle of the Sphere, movable, described from the North Pole of the Ecliptick, by the Mo­tion of the Primum Mobile. The Po­lar Antartick, is a lesser Circle of the Sphere, movable, described from the South Pole of the Ecliptick, by the motion of the Primum Mobile.

They let us see first, the Poles of the Zodiack, and they measure their distance from the Poles of the World. 2. They bound the Temperat Zones, and sepa­rats them from the Cold Zones, which [Page 34] are bounded and inclosed by their cir­cumferences. It is to be observed, that the antient Astronomers, Proclus, Cleo­medes, and the rest, had not the same description of the Polars, which we have. For the Antients, did not de­scribe them, as passing thorow the Poles of the Ecliptick, but thorow the com­mon Sections of the Meridian, and Ho­rizon, equidistant to the Equinoctial▪ and therefore, so much was their di­stance from the Poles of the World, a [...] the height of the Pole was above the Horizon. And by this means, where there is no Elevation of the Pole, as in a Right Sphere, there are no Polars. But from thence, they are more, and more gradually augmented, and enlarg­ed, according to the increment of the Poles Elevation.

The uses of the Polars, according to the Antients, are these, 1. They com­prehend the Arch of the Elevation of the Pole. 2. Of all the Parallels of the Equinoctial, which are always seen a­bove the Horizon, they are the greatest [Page 35] and of all the Parallels of the Equino­ctial, which ly hid under the Horizon, they are the greatest also. But contra­ [...]iwise, of all the Parallels of the Equi­noctial, which arise and set in twenty four Hours, they are the least. There­fore (3.) the foresaid Polars, compre­hend within their Compass, and Circle, [...]he whole Stars and Points of Heaven, which are always in sight, and do not [...]et. Hence, there ariseth a threefold [...]istinction of the Stars. 1. There are [...]ome, which have a perpetual Day, and [...]ever set, or fall under the Horizon, to [...]it, those which are comprehended within the Circle of the Polar Artick. 2. There are others, which have a per­petual Night, which never rise, or come [...]p above the Horizon, to wit all those, which are included within the Circle of [...]he Polar Antartick. There are (3.) o­thers which both rise and set in four [...]nd twenty Hours, to wit those, which [...]ither on this side, or that side of the Equinoctial, tend towards and come nearest to the foresaid Polars.

CHAP. IX. Concerning other Circles of the Sphere, both greater and lesser, which cannot be conveniently drawn upon it.

BEside the Circles of the Sphere hi­therto explained, there are yet in­numerable more, both of the greatest and lesser sort, which Astronomers have excogitated for attaining a more perfec [...] knowledge of the Heavenly Motions▪ 1. There are of the greatest sort Verti­cals, which pass thorow every point o [...] the Horizon, cutting one another there which by the Arabians are called Azi­muths. 2. There are the Horary Cir­cles, which divide the Heavens, into four and twenty parts, which are o [...] three sorts. For either they have the beginning in the Meridian, and pa [...] thorow the Poles of the World, or the have their beginning in the East, o [...] West-part of the Horizon, by whic [...] [Page 37] means they touch lightly, the two Cir­cles lying parallel to the Equinoctial, of which one is the greatest of all, which are always seen above the Horizon, the other the greatest of all, which are not seen above the Horizon: or lastly, they have their beginning in the Horizon, but neither go thorow the Poles, of the World, nor go near to the foresaid Pa­rallels, but divide all the Segments of the Parallels, which are above or be­low the Horizon, into twelve equal parts. 3. There are Circles of Decli­nation, which pass thorow the Poles of the World, and every point of the Equi­noctial. There are 4. Circles of Lati­tude, which pass thorow the Poles of the Ecliptick, and every one of his Degrees.

The lesser Circles are infinite also; for there is no great Circle, which hath not his own Parallels. As first the Ho­rizon, which hath Circles of Altitude, called by the Arabians Almicanthars. The Equinoctial, hath its own Parallels, to wit, described by the Primum Mo­bile, [Page 38] from all, and whatsoever Points are in the Heavens. So hath the Zo­diack his Parallels, described about the Poles of the Ecliptick, which Parallels every Star, or point of the Heavens, ac­cording to the proper motion of the eight Sphere, do describe, and many more are there invented by Astrono­mers for Astronomical uses.

CHAP. X. Of the Zones.

TO the Doctrine of the Sphere, is commonly annexed the Geogra­phical Tractat of the Zones. The Zones therefore are nothing else, but as much bounds, of the Heaven, or of the Earth, as is comprehended between both the Tropicks, or between either of the two Tropicks, and the next Polar, or be­tween either of the two Polars, and the neighbouring Pole. Therefore the [Page 39] Zones, are either Celestial, or Terre­strial. The Celestial Zones, are bound­ed by themselves, and their own Circles in the Heavens. The Terrestrial Zones, ly directly under the same places of the Heavens. They are five in number, one Torrid, two Temperate, and two Frigid. The Torrid Zone, is that space of the Heavens, or the Earth, compre­hended between the two Tropicks. This is divided into two parts, of which one is called the Northern, the other the Southern part. It is called Torrid, because here, the Rays of the Sun are more perpendicular, and so hotter, that the Inhabitants are in a manner scorch­ed, and burnt up with Heat. The Temperate Zones, are that space of the Heavens, or of the Earth, comprehend­ed between either of the two Tropicks, and the neighbouring Polars: and that which is included, between the Tropick of Cancer, and the Polar Artick, is cal­led the Temperate Northern Zone, wherein are contained, all Europe al­most, and a great part of Asia, and also [Page 40] a part of America. But that which is included between the Tropick of Capri­corn, and the Antartick Polar, is called the Southern Temperate Zone. This contains more Sea, and less Land. They are called Temperate, because the Rays of the Sun, being more oblique, there is not such a reflection of Heat, but of­fer a most commodious Dwelling to the Inhabitants. The Frigid Zones, are that space of the Heavens, and of the Earth, comprehended between either of the Polars, and the neighbouring Pole of the World. And that bounds, which is included between the Polar Artick, and the North Pole, is called the Northern Frigid Zone: and that bounds which is included, between the Polar Antartick, and the South Pole, is called, the Southern Frigid Zone. They are called Frigid, because the Rays of the Sun are most Oblique, and are absent almost half a Year; so that all things become rigid and stiff, with Frost, Yce, and Snow. In this Zone, lyes Island and Greenland, but in the [Page 41] Southern cold Zone, the parts are un­known to us.

The Inhabitants of the five Zones, have obtained divers names. For those, who inhabite the Torrid Zone, are called Amphiscii, as having a shadow on both sides. I say on both sides, in respect of the Vertical Point. For the Sun with them, is sometimes on this side, and sometimes on that side of their Ver­tical Point: sometimes the shadow of their Dials is projected from South to North, and sometimes from North to South, when he is in the Meridian. The Inhabitants of the Temperate Zones, are called Heteroscii, as having but one shadow. For at 12 a Clock in the Day, the shadow is either casten to­wards the North, as with us, or to­wards the South, as with those, who dwell in the Southern Temperate Zone. But those, who live in the Frigid Zones, are called Periscii, as having a shadow, which goes round about them; because they have the Sun for several Months of the Year, above their Horizon, and [Page 42] the Heavens there, like a Milstone, is whirled about, so that the Sun and Stars describe Parallels to the Horizon, and therefore in four and twenty Hours, he runs about without rising and set­ting, and projects his shadow into an Orb, or Circle.

There are likewise, the Antipodes, Anteci, and Perieci. Antipodes, are those, who have the same Meridian, but dwell in points of it, diametraliter opposite, and are under opposite Parallels, (to wit in an oblique Sphere,) of which the one is Southern, the other Northern. These following Phenomena, are proper to them. 1. Though they have the same Rational Horizon, yet beholding the opposite Faces, all things fall out to them contrariwise. For when we have Day and Mid-day, our Antipodes have Night and Mid-night. When we have Summer, they have Winter. When the Sun rises to us, he sets to them. We have North Latitude, they have South Latitude.

The Anteci are those, who dwell un­der [Page 43] opposite Parallels, equally distant from the Equator, towards both the Poles, under the same Meridian, but not in Points diametraliter opposed, but in a Semi circle of the Meridian inter­cepted between the Poles. They have these Phenomena proper to them. First, They agree in the same Longitude, and Latitude; for how much is the South Pole elevated to those, so much is the North Pole elevated to these. 2. In the same Moment of Time, both of them have the Sun in their Meridian. But in this they differ; while the Sun is coming to the Tropick of Cancer, those have Summer and longer Days, but these have Winter, and shorter Days. Again, when the Sun is returning, those have Harvest, the Days Decreasing, but these have the Spring, the Days Increasing. Hence it is, that the Sun doth not rise, and set to both, at the same time.

The Perieci are those, who dwell un­der the same Parallel and Meridian, but in Points of the same Parallel diametra­liter [Page 44] opposite; so that both of them be­hold the same Pole, with equal height above the Horizon. First, They dwell in the same Zone. Secondly, They have the same Elevation of the same Pole. They have the same Winter, the same Summer, the same longest Day, and the same increment, and decrement of the Natural Days. But here they differ; those having the Sun rising, these have it setting; those having the Sun in the Meridian, these have it at our Mid-night: and contrariwise, when to those the Sun is setting, to these he is rising, when to those it is Mid-night, to these it is the Meridian.

CHAP. XI. Of the Rising and Setting of the Stars ac­cording to the Poets.

HItherto we have treated of the Hypotheses, to wit, the Circles of the Sphere, which so much conduce [Page 45] for explaining the Phenomena of the Primum Mobile. It now remaineth, that we speak and treat of the thing it self, to wit, the Phenomena themselves. And in the entry, we ought to have spoken of the rising and setting of the Stars, called Ortus & occasus stellarum Astronomicus; but the knowledge of those things, cannot be taught here com­pendiously, nor without the Science of Spherical Trigonometry; therefore pas­sing this, we come to explain the rising and setting of the Stars, called Ortus & occasus Poeticus, which is the second Phenomenon of the Primum Mobile.

This rising and setting of the Stars according to the Poets, is nothing else, but the rising of a Star above the Ho­rizon, and the setting of a Star under it, in relation to the various Position of it, with the Sun. It is called Poetical, not because it doth not belong to Astrono­mers; for it is a part of their Science to determine those Risings and Settings, but because the Poets in describing cer­tain [Page 46] Seasons of the Year, use this me­thod, as will be seen afterward.

Of this Poetical Rising and Setting, there are three forms. First, That which is called the Rising and Setting of a Star Cosmice. Secondly, That which is cal­led the Rising and Setting of a Star, A­cronyce. Thirdly, That which is called the Rising and Setting of a Star Heliace. Each one of those hath a double signifi­cation; one general, the other special. The Rising of a Star Cosmice generally taken, is the Rising of a Star above the Horizon, falling out from the Rising of the Sun to his Setting. The Setting of a Star Cosmice, generally taken, is the Setting of a Star, falling out from his Rising to his Setting. The Rising of a Star Acronyce, generally taken, is the Rising of a Star above the Horizon, fal­ling out the whole time, the Sun is un­der the Horizon. The Setting of a Star Acronyce generally taken, is the Setting of a Star under the Horizon, falling out all the time the Sun is under the Hori­zon. The Rising of a Star Heliace gene­rally [Page 47] taken, is the appearing of a Star after the Sun is Risen. The Setting of a Star Heliace generally taken, is the disappearing of a Star, after the Sun is set. But their special signification de­notes, and determines, a certain, and definite time. Therefore, the Rising of a Star Cosmice, is the ascending of a Star above the Horizon, in the same mo­ment, wherein the Sun Rises. The Set­ting of a Star Cosmice, is when a Star goes down, while the Sun is Rising. The Rising of a Star Acronyce, is when a Star comes above the Horizon, the Sun go­ing down under the Horizon that same moment. The Setting of a Star Acrony­ce, is when a Star Sets with the Sun, that same moment. The Rising of a Star Heliace, is when a Star, which could not be seen, by reason of its nearness to the Sun, is now seen in the night time. The Setting of a Star Heliace, is when a Star, by reason of the Suns great distance from it, might have been seen in the night time, but the Sun coming nearer to it, it disappears out of our sight.

[Page 48]We have an Example of the Rising of a Star Cosmice, in the first Book of the Georgicks.

Vere fabis satio: tunc te quoque Medica putres
Accipiunt sulci, & Milio venit annua cura
Candidus auratis aperit, cum Cornibus an­num
Taurus, & adverso cedens Canis occidit Astro.
When Taurus with his gilded Horns,
Begins the Year, then Sowe your Corns
Sowe Millet-seed, an yearly toil,
Sowe Claver-grass, in putrid soil,
Sowe yearly Pulse, and what you please
Sowe in the Spring, both Beans and Pease.

Virgil doth express here the Spring time, when the Millet-seed is to be sown [...] which is in the beginning of April: An [...] seing the Sun at that time, is about th [...] [Page 49] end of Aries, it must be understood of the Rising of Taurus, which at that time riseth with the Sun Cosmice. At this time the Romans used to sowe their Beans, their Claver-grass, and their Mil­let, which every year must be renewed; whereas the Claver-grass is to be sown but once in ten years.

We have likewise an Example of the Set­ting of a Star Cosmice, from that same place in Virgil.

Ante tibi Eoae Atlantides abseondantur
Gnosiaque ardentis decedat stella Coronae
Debita quam sulcis committas semina.
When Pleiades, the Maidens seven,
Are set into the Western-Heaven,
When Ariadnes Crown full bright
Before the Sun comes in our sight,
Then sowe your Ground with Wheat and Rye
'Tis of October eighteen day.

Before you sowe your Ground (says [Page 50] he) let the Pleiades, or Seven-stars be set, which about October 18, go down in the West, in the same Moment of Time, while the Sun is Rising in the East, which is called Occasus Cosmicus.

We have an Example of the Rising of a Star Acronyce, from Ovid, in his first Book de Ponto.

Quatuor autumnos Pleias orta facit.
Four Harvests surely there have been,
For Pleias four times have been seen.

Ovid is here speaking of the Harvest time, when the Sun is in Scorpio, there­fore when the Sun is Setting, Taurus or the Bull, and the Pleiades are Rising Acronyce.

[Page 51]We have also an Example of the Set­ting of a Star Acronyce, from the same Ovid, in his second Book of his Fasts.

Illa nocte aliquis tollens ad sidera vultus
Dicet ubi est hodie, quae Lyra fulsit heri.
Last Night when I surveyed the Sky,
saw the Harp, 'tis gone away
This Night.

This time, is the second day of Fe­ [...]uary, at which time the Constellation [...]lled the Harp, sets Acronyce, with the [...]u.

We have likewise an Example of the Rising of a Star Heliace, from the first Book of the Georgicks.

Gnosiaque ardentis decedat stella Coro­nae.
When Ariadnes Crown full bright
[Page 52]Before the Sun comes in our sight.

'Tis eviden [...] that Virgil speaks here of the Rising of this Constellation He­liace, called Aridnes Crown, when the Sun is in the beginning of Scorpio. For seing this Constellation rises at Rome, where Virgil lived, with the 27 Degree of Virgo, it is needful to conceive this Crown to be seen in the Morning, the Sun being yet under the Horizon.

Note, That there is a Figure called Hypallage in the word Decedat: for the Crown doth not recede from the Sun, but the Sun from it.

And lastly, We have an Example of the Setting of a Star Heliace, from the same place of Virgil.

Taurus, & adverso cedens Canis occi­dit Astro.
And when the Dog shall disappear,
By Phebus Beams him coming near.

[Page 53]The Poet is here speaking of the Suns ingress into Taurus, which fell out in Virgils time on the 1 [...] of April. But seing the Dog-star sets at Rome with the 22 Degree of Taurus, therefore, the Sun setting in the Evening, the Dog­star setteth Heliace, or disappears out of our sight, by reason of the Suns Rays, which now are nearer him.

Observe, That what Stars do arise Cosmice, which is also called Ortus Ma­tutinus, they set Acronyce, which is cal­led Occasus Vespertinus: and what Stars do arise Acronyce, which is called Ortus Vespertinus, they set Cosmice, which is called Occasus Matutinus, according to the following Rhyme.

Cosmice descendit signum, quod Chronice surgit,
Chronice descendit signum, quod Cosmice surgit.

Aliter.

Mane vehit supra terram tibi Cosmicus ortus
[Page 54]Sidera, sed Phoebi lumine tecta latent.
Mane dat Heliacus quaedam subvecta vi­dere
Astra, sed Achronycus nocte videnda tra­hit.

Note secondly, That the word Cos­micus, comes from Kosmos, the World. That the word Chronicus, comes from the Greek word Chronos, Time. But Acronycus comes from Acra & Nux, which is the first part of the Night, or the Evening▪Twilight. That Heliacus comes from Helios, the Sun. Lastly, That Chronice, and Acronyce have the same signification.

CHAP. XII. Concerning the Natural, and Artificial Days.

NOw follows another Phenomenon of the Primum Mobile, to wit, the Doctrine of Days Natural and Artifi­cial. [Page 55] Days are twofold, Astronomical, and Civil. Astronomical Days, are such as are measured, by the Revolu­tions of the Equinoctial, and deter­mined by a certain quantity. Days Civil, are such as every Nation, accor­ding to their own Custom make use of. The Astronomical Day, is either Na­tural, or Artificial. The Natural Astro­nomical Day, is a space of time, where­in the Sun, by the Motion of the Pri­mum Mobile, being carried about, from whatsoever immovable point of the Hea­vens, returns to that same point again. These Astronomical Days have their be­ginning in the Meridian, as was insinuate before. The Artificial Astronomical Day, is a Space of Time, wherein the Center of the Sun remains above the Horizon. And the Artificial Night, is as much Time, as the Center of the Sun remains under the Horizon.

The Doctrine of the Artificial Days and Nights, is contained in the follow­ing Theorems. 1. The Artificial Days and Nights, with the Amphiscii, Hete­roscii, [Page 56] and partly with the Periscii, are parts of the Natural Day: but with the Periscii, in those parts of the Earth, wherein the Sun, by the going about of the Primum Mobile, perfects some Circumgyrations, either above the Ho­rizon, without setting, or under the Horizon, without rising, one Artificial Day, or one Artificial Night, doth ex­cresce into many Natural Days; so that indeed under the Poles, the Artificial Day contains half a Year, and the Ar­tificial Night as much; and so to speak properly, the whole Year consists but of one Day, men looking to the Analo­gy of the Natural Day. 2. Under a Right Sphere, the Artificial Day, is equal to the Night: for the Horizon, in this Position of the Sphere, cuts the Circuli Dierum, the Day-Circles, into two equal parts. The Day-Circles, are called those Parallels of the Equator which the Sun doth dayly describe, by the Motion of the Primum Mobile. 3. In an Oblique Sphere, there are only twice a Year, two Equinoxes, when the Sun [Page 57] is in the beginning of Aries and Libra. The Reason of this appears, from the mutual Section of the Horizon, with the Circuli Dierum, or Day-Circles, which is indeed unequal, except when the Sun is in the Equinoctial. 4. In an Oblique Sphere, which hath the vicissi­tude of the Artificial, and Natural Day, by one Revolution of the Equator, the Sun being in the. Tropick of Cancer (we are now speaking of this upper­most part of the Sphere) we have the longest Day in all the Year, and the shortest Night: but the Sun being in the Winter Solstice, the Day is shortest, and the Night longest. 5. In the same Position of the Sphere, thorow the whole half of the Ecliptick descending, the Sun maketh the following Days shorter, than the Days going before, but the Nights longer. But in the half of the Ecliptick ascending, the Sun maketh the Days following longer, than the Days going before, but the Nights shorter. 6. When the Sun is existing, in places of the Ecliptick, equally di­stant, [Page 58] from the same Solstitial Point, Days are equal to Days, and Nights to Nights. 7. When the Sun is existing in places of the Ecliptick equally di­stant, from the same Equinoctial Point, the Day of one Place, is equal to the Night of another. 8. In an Oblique Position of the Sphere, the greater the Elevation of the Pole is, the greater are the increments of the longest Day, and shortest Night, until coming under the Polars, the longest Day contains twen­ty and four Hours. 9. In an Oblique Sphere, of such as dwell between the Polar, and next Pole, the longest Day excresceth into many Natural Days, as also the longest Night. But there are certain intermediat Horary Circles, a part of which is above the Horizon, and a part under, in which, when the Sun is existing, the Artificial Days, as also the Nights, are▪ parts of the Natu­ral Day. 10. In a Parallel Sphere, such as they have, who live under the Poles, the whole Year, is divided into one Artificial Day, and one Artificial Night.

[Page 59]The length of every Artificial Day, is known by the Diurnal, and Nocturnal Arch. First, find the Oblique Ascension or Point of the Equinoctial, which ris­eth with the Sun, and Oblique Descen­sion, or Point of the Equinoctial, which setteth with the Sun. Subtract the les­ser from the greater, and half the diffe­rence, is the Ascensional difference, which added to six Hours in the Sum­mer half Year, but subtracted therefrom in the Winter half Year, gives half the Diurnal Arch, whose double is the whole Diurnal Arch, and the Complement of the Diurnal Arch to 24 Hours, is the Nocturnal Arch. For Example, The tenth day of April 1687, the Oblique Ascension of the Sun (being in the first Degree of Taurus) is 10 deg. 21. m. the Oblique Descension is 45 deg. 27 m. whose difference is 35 deg. 6. m. whose half is 17 deg. 33 m. the Ascen­sional difference, which being added to 90 deg. or 6 Hours, is 107 deg. 33 m. which make 7 hours, 10 m. fere, for the time of the Suns setting, which is [Page 60] always half the Diurnal Arch. There­fore the Diurnal Arch is 14 hours, 20 m. Which taken from 24 hours, there remains 9 hours, 40 m. for the No­cturnal Arch required. Note, That the Ascensional difference added to the Oblique Ascension in the Summer half Year, but subtracted from it, in the Winter half Year, gives the right A­scension of the Sun, or any of the Stars.

What is said of the Day in respect of the Sun, may be most commodiously applyed to the Stars. For the Day of a Star, is rightly called the space of Time, wherein it is above the Hori­zon: and the Night of a Star, the space of Time, wherein it is below the Hori­zon. Concerning the days of the fixed Stars, let the following Theorems be observed. 1. In a Right Sphere, the Stars have a perpetual Equinox. 2. But in an Oblique Sphere, the fixed Stars, whose North Declination, is greater than the Complement of the Altitude of the Pole, are said to have an Eternal Day: but those Stars, whose South De­clination, [Page 61] exceeds the Complement of the Altitude of the Pole, are said to have an Eternal Night. The interme­diate Stars, have the course of rising and setting. 3. In a Parallel Sphere, the fixed Stars are said to have Eternal Days, and Eternal Nights.

Days Civil, are called the space of Time, of one Revolution of the Equi­noctial, which according to every Na­tion, or Countrey, is divers ways be­gun, and made use of. For as there are various and divers Nations in the World, so each one hath a different way of be­ginning their Hours. For the Iews, by Divine Institution, began their Day, from the setting of the Sun, which cu­stom the Italians do observe. The Ba­bylonians began their Day from Sun ri­sing, whose practice, the Norinbergers, the People called the Umbri, and the Egyptians do imitate. The Arabians as the Astronomers, begin their Day from the Meridian. The Romans from Mid­night. The Germans, the Frenches, and Spainards begin their Day from the [Page 62] Meridian, and Mid-night. For their Clocks, and Watches are so contrived, that they return from one a Clock in the Night-time, to twelve a Clock in the Day-time, and from one a Clock in the Day-time, to twelve a Clock at Night-time. Their Days are divided, as the Astronomical Days, into one Ar­tificial Day, and likewise into Forenoon, and Afternoon.

And because Hours are parts of the Days, therefore we must speak a little of them. The Hour is the twentieth and fourth part of the Natural Day, or the space of Time, wherein the twen­tieth and fourth part of the Equino­ctial, or 15 Degrees thereof, riseth a­bove the Horizon. But this Definition is not sufficient, because it doth not agree to all Hours: for every twelfth part of every Day, and every Night whatsoever, was called by the Iews, and the Antients an Hour. But 15 De­grees of the Equinoctial, do not al­ways ascend above the Horizon, every one of these Hours; but sometimes [Page 63] more, and sometimes fewer, as will ap­pear afterward. Therefore, an Hour may rather be defined thus, a certain part of the Artificial Day, and Night, made use of by divers Nations, after a divers manner, that it may be known generally, what the Hour is. For in effect, that definition agrees only to to those Hours, which are called Hor [...] Aequales, equal Hours. The Hours then, which are called unequal, ought to be defined thus. The twelfth part of every Artificial Day and Night: therefore according to the divers Sea­sons of the Year, the Hours are some­times shorter, and sometimes longer: in Summer longer, and in Winter shor­ter, as are th [...] Iewish Hours: for they divide both the Day, and the Night in­to twelve parts, both in Summer and in Winter, calling the rising of the Sun, the beginning of the first Hour, and consequently nine their third Hour; twelve their sixth Hour, three a Clock in the Afternoon their ninth Hour, and the setting of the Sun, the end of their [Page 64] twelfth Hour, by which means, their Hours must be far longer in Summer, than in Winter.

The equal Hours are of three sorts: for some take their beginning from the setting of the Sun, as the Italian Hours. Others take their beginning from the rising of the Sun, as are the Babylonish Hours, and the Hours of the City of Norimberg, who from the rising of the Sun begin the number of the Hours of the Day; the Circles of which Hours do lightly touch the greatest Parallels, of all, which do appear above the Ho­rizon, and of all which do not appear. Lastly, Others do take their beginning from the Meridian, which Astronomers make use of, and these Nations, which either take their beginning of Hours from the superior part of the same Cir­cle, or from the inferior part.

CHAP. XIII. Concerning Years.

AS Hours make up Days, so Days make up Years, therefore we must speak somewhat of Years. The Year then is twofold, Astronomical, and Po­litical. The Astronomical Year, is the space of Time, wherein the Sun returns, either to the same Point of the Ecliptick, or to the same fixed Star. And this is twofold, the Tropical Year, called An­nus Vertens, or the Syderial Year. An­nus Vertens, is a space of Time, where­in the Sun leaving some Point of the Ecliptick, returns again to the same Point. The quantity of this Year is changeable; for sometimes it is more, and sometimes it is less. Between these two extreams, the middle Year contains 365 days, hours 5, m. 49, sec. 15. thirds 46. But the true or apparent Year is sometimes 365 days▪ hours 5, [Page 66] min. 56. sec. 53, thirds 1. Sometime it is 365 days, hours 5, min. 42, sec. 28, thirds 27. The Syderial Year, is a space of Time, wherein the Sun un­der the Starry Sky, returns to the same fixed Star. The quantity of this Year is 365 days, hours 6, min. 6, sec. 39. It is always equal to it self, and there­fore the measure of the Year called An­nus Vertens. The beginning of this Annus Vertens, is taken from the Vernal Equinox, but the beginning of the Sy­derial Year, from the first Star of Aries.

The Political Year, is an Annual space of Time, which is either accom­modated to the course of the Sun, or the Moon, or to both, according to the common reckoning of several Countries and Nations. This Political Year is manifold; for it is either Iulian, which contains 365 days, hours 6, which six Hours, if they were reckoned every Year, would make confusion: there­fore the Masters of Astronomy have ap­pointed, they should be omitted, till the fourth Year, and then four times six, [Page 67] make 24, which make up a full and compleat Day, which being inter caled, that is, interlaced, or put between, as in Leap Year there is a Day put be­tween the 28 of February, and the first of March, the Year is called Annus In­tercalaris, or Bissextile Year. It is to be adverted, that the cause of correcting the Iulian Calendar, by Pope Gregory the 13, in the year 1582, was the un­just quantity of it. For by this, it came to pass, that after some Ages, the four Cardinal Points did anticipate and pre­vent their Seats; and so at length the four Seasons of the Year, might be in­terchanged. From this it is evident this Day, that according to these times, the Equinoctial, and the Ingress of the Sun into the 12 Signs have anticipated almost 13 Degrees. That is, the en­tering of the Sun, into Aries, Taurus, &c. falleth out sooner by 13 Degrees, than to the Romans: which comes to pass, because more, than what is just, is given to the space of the Year. For there were given to the Year, by the corre­ction [Page 68] of Iulius Cesar, 365 days, and six hours: for which hours, every fourth year, one day is added, and so the com­mon Iulian year contains 365 days, but the Bissextile 366. But seing the Solar year, in which the Sun runs thorow the whole Ecliptick, is less than this space, by almost eleven Minuts of Time every Year; it comes to pass, that in 50 year, and a half, one hour remains, and in the space of 130 years, a whole day remains.

I said the Political Year, was mani­fold, either Iulian, of which hitherto, or Egyptian, or Iudaical. The Egyp­tian year contains always 365 days. This Year was esteemed most useful by the antient Astronomers, for the Art of reckoning the Celestial Motions. The Iudaical Year is accommodated and fitted to the Motion of the Moon, and contains, for the greatest part, twelve, and sometimes thirteen Lunations. This Year did the Astronomers use, before the reformation of the Calendar, insti­tuted by Iulius Cesar, by the help of [Page 69] one Sosigenes, a famous and learned Ma­thematician. The beginning of these Years is divers also. For the antient Romans, began their Year from March: the later Romans from the midst of Win­ter, called Bruma. The Iews, by Di­vine Institution, began their Year from the New Moon, which was next after to the Vernal Equinox. That we this day begin our Year from the first of Ianuary, it is for this, because we fol­lowing the custom of the late Romans, beginning their Year from the midst of Winter, which was nearest to the first of Ianuary, by little and little the Win­ter Solstice did prevent, and anticipat its Seat, and Place. The Egyptian year, hath not a sure beginning, by reason that six hours are omitted. Hence is it, that every fourth Year it anticipats one Day: and therefore within 365 Years, four times numbered, or 1460 Iulian Years, the beginning of the Egyptian Year, wanders over all the Days of the Iulian Year.

CHAP. XIV. Concerning the divers Phenomena, which are to be seen in the various Positi­ons of the Sphere.

THe last part of this little Tractat, shall be in examining the Pheno­mena, which are proper to the various Situations, and Positions of the Sphere. The Sphere may have seven different Positions, 1. When both the Poles of the World do rest in the Horizon, which is called a Right Sphere. The second Po­sition is Oblique, when our Vertical Point, is terminated between the Equi­noctial, and either of the Tropicks. The third Position is, when our Zenith is un­der either of the Tropicks. The fourth is, when our Zenith is between either of the Tropicks, and the neighbouring Polar. The fifth is, when our Zenith is in the very Polar itself. The sixth is, when our Zenith is between either of [Page 71] the Polars, and the neighbouring Pole of the World. And lastly, when the Poles of the World, do fall in with the Poles of the Horizon, which is called a Parallel Sphere.

CHAP. XV. Concerning the Phenomena of the first Position.

1. EVery Star in the Heavens riseth and setteth, neither is there one of them, without this property: and therefore in this Position, there is nei­ther Polar Artick, nor Antartick, ac­cording to the Antients. 2. There is here a perpetual Equinox. 3. The Sun every Year passing twice over their Heads, is to them twice Vertical, to wit, when he is in the Equinoctial Points. 4. As much, as the Sun declines from their Vertical Point, towards the North, as much also doth he decline from their [Page 72] Vertical Point, towards the South. 5. They have four Solstices, two when the Sun is highest in their Vertical Point, and two, when he is lowest, in Cancer, and Capricorn. 6. They have two Sum­mers and two Winters, but only Ana­logically: for even in Winter, their Bodies are scorched with heat. 7. There are here in this Position, five different Shadows, the Meridional, or South Shadow, the North Shadow, a Shadow from the East, a Shadow from the West, and a perpendicular Shadow, which falls out only, when the Sun is in the Equinoctial Points. 8. The end or ex­tremity of their Gnomons, upon their Horizontal Dialls, which are our Polar Dialls, describe the whole Year, the Fi­gure called Hyperbole, except when the Sun, is in the beginning of Aries and Libra, where he describes a straight and right Line.

CHAP. XVI. Of the Phenomena of the second Position▪

1. SOme Northern Stars tarrying al­ways above our Horizon, have Eternal Days; and contrariwise, there are some about the South Pole, which never come above the Horizon, but have Eternal Nights. 2. The Artick, and Antartick Circles, according to the Antients, are not as yet equal to our Polars. 3. The Artificial Day is not equal to its own Night, two Days only ex­cepted, when the Sun is in the Equino­ctial Points, at which time, there is thorow the whole World an Equinox. 4. The longest Day there, doth not ex­ceed thirteen Hours and a half. 5. The Sun is to them, twice Vertical every Year, to wit, when he comes to those Degrees of the Ecliptick, whose Decli­nation, is equal to the Latitude of the Place; for he describes then, a Parallel [Page 74] thorow the Zenith. 6. The Sun in the Meridian, goeth further towards the South, than towards the North. Note, That we are now speaking, and in the following Discourse, of those seven Po­sitions, which are in the Northern Sphere. 7. There are here, four Sol­stices, two high, and two low. The two highest fall out, when the Sun is in that Parallel, which passeth thorow the Zenith. The two lowest are, when the Sun is in the Tropicks. Yet that which falls out in the Tropick of Capricorn, is lower, than that which falls out in the Tropick of Cancer. 8. They have two Summers, and two Winters, but une­qual, as appears from the various Situa­tion of the Parallels. 9. The longest Day is not, when the Sun is in the highest Solstices, but in the Tropick of Cancer. 10. There are five different Shadows, as we observed in the first Position. 11. The end or extremity of the Gnomon, by its Shadow, when the Sun is out of the Equinoctial, de­scribes (as in the first Position) the [Page 75] Figure called Hyperbole, but the oppo­site sides are not equal as there, but un­equal. 12. In any part of this Position, where the Elevation of the Pole, is less, than the Declination of the Sun, the Shadow of a Style perpendicularly e­rected upon a Plain, may have a natu­ral, visible, Retrocession. In the mat­ter of Ahaz his Dial, the Retrograda­tion of the Shadow was miraculous, be­cause it was done without, and not within the Tropicks, neither is it possi­ble in nature, it can happen, but where the Elevation of the Pole, is less than the Suns Declination, which is only within the Tropicks. But the foresaid Dial was placed far without, to wit, under the Latitude of 35 Degrees.

CHAP. XVII. Of the Phenomena of the third Position.

1. ALL the Stars, which are com­prehended within the North Polar, remain always above the Hori­zon, neither do they ever set, unless it be, by a general setting Heliace: and contrariwise, all the Stars, which are comprehended within the South Polar, have a perpetual Night▪ therefore the Polars, according to the Antients, are now equal to our Polars. 2. The longest Artificial Day is, when the Sun passeth over our Zenith; the shortest, when the Sun is farthest in the Meridian removed from it. 3. Once a Year on­ly is the Sun Vertical, to wit, when he is in the beginning of Cancer. 4. The Sun in the Meridian, never descendeth from the Zenith towards the North, but returning from the Tropick of Can­cer, he is alway in the South. 5. There [Page 77] are here, but two Solstices, one high, another low. The highest, when the Sun is in the Tropick of Cancer; the lowest when the Sun is in the Tropick of Capricorn. 6. The Day is longest, when the Sun is in the Tropick of Cancer, it is shortest when the Sun is in the Tropick of Capricorn. 7. There is one Summer, when the Sun is in the Zenith, and one Winter, when he is in the Winter Solstice. 8. They have four different Shadows, one Perpendicular, one Oriental, one Occidental, and one Meridional. Here begin the Heteroscii, for the Meridional Shadows begin there to decay, that is, the Shadows project­ed towards the South. 9. The extre­mity or end of their Gnomon, upon their Dials, describe also the Figure cal­led Hyperbole, the sides opposite being unequal.

CHAP. XVIII. Of the Phenomena of the fourth Position.

AS the Artick and Antartick of the Antients, are greater than our Po­lars, so there are more Stars in this Po­sition of the Sphere, seen perpetually, and more perpetually lurking under the Horizon, than in the last Position. 2. The unequality of Days and Nights, are also augmented. The Artificial Day is at the longest, when the Sun comes nearest to our Zenith, and at the short­est, when he is furthest removed from it: and as the shortest Artificial Day cannot be less, than 13 Hours and a half, so the longest Day cannot be 24 Hours. This least Artificial Day, is truly the longest Day, our Vertical Point coming nearest to the Tropick. It is called the least Artificial Day, because it is the shortest of all the longest Days, which can arise from the variation of [Page 79] the Vertical Point, between the Tropick and the Polar: and therefore, itis not cal­led Minima the least, in respect of the rest of the days of the same Elevation of the Pole, but in respect of the rest of the longest Days, which may be found be­tween the Tropick and Polar. The longest Day in this fourth Position of the Sphere, the Zenith coming nearest to our Tropick, cannot be less, than 13 Hours and a half, as the longest Day cannot contain 24 Hours. For this comes to pass, when the Zenith is in the Polar: therefore we must read, as the shortest Artificial longest Day, cannot be less, than 13 Hours and a half, &c. 3. The Sun can never come to their Ze­nith, neither can he ever touch lightly ( stringere) their Horizon, when he is in the Meridian. 4. There are two Solstices, one when the Sun is in Cancer, and highest, another lowest, when he is in the Tropick of Capricorn. 5. There is one Summer, and one Winter. 6. There are only three different Shadows, one Oriental, the second Occidental, and [Page 80] the third Northern. 7. The extremity or end of their Gnomons, fixed upon the Ground perpendicularly, describe as yet Hyperboles.

CHAP. XIX. Of the Phenomena of the fifth Position.

ALL the Stars, whose distance from the Equinoctial, is greater than the Obliquity of the Ecliptick, either do not set under the Horizon, if they be Northern Stars, and do not rise above the Horizon, if they be Southern Stars: Therefore the Artick, and Antartick of the Antients are equal to the Tropicks. 2. The longest Day contains 24 Hours, and then there is no Night: and con­trariwise, the longest Night consists of twenty and four Hours, and the Artifi­cial shortest Day is nothing. 3. The Sun every year toucheth lightly the border of the Horizon twice, without rising and setting, namely when he is in [Page 81] the Tropicks. 4. The Sun at twelve a Clock in the Day, is alway South, nevertheless, when he is in the Tropick of Cancer, the half of his Body may be seen in the North, at 12 a Clock at Night. 5. There are here two Sol­stices, one high in Cancer, the other low in Capricorn. But according to the simi­litude of Solstices, which are in other Zones, we may say there are three Sol­stices there, one high in Cancer, when the Sun is high in the Meridian, to wit, 47 Degrees above the Horizon, which is the distance of the Tropicks; there are two lower, of which one is in the same Tropick of Cancer towards the North, when he toucheth lightly the border of the Horizon, the other in the Tropick of Capricorn, where he also light­ly toucheth the border of the Horizon. 6. There is one Summer, and one Win­ter. 7. There are four different Sha­dows; one Eastern, one Western, one Northern, and one Southern; tho this happens but once a Year, the Sun shine­ing with the half only of his Rays, which [Page 82] makes the light more obscure and dark, than when he shines with his full Rays. Here begin the Heteroscii. 8. The ex­tremity or ends of the Gnomons, de­scribe the Figure called Parabola, upon the Horizontal Dials, but an Hyperbole, so soon, as the Sun is gone from the Equinoctial, whereas on all other Plains, he describes always straight and right Lines.

CHAP. XX. Of the Phenomena of the sixth Position.

THere are very few Stars, which can rise or set, to wit, those on­ly, whose Declination is less than the distance of the Tropicks; because the Artick, and Antartick Circles, compre­hending within them, the Stars which do set, and do not set, are greater than the Tropicks. 2. They have an Equi­noctial, as other parts of the Earth. But when the Sun is in that Parallel [Page 83] whose Declination from the Equino­ctial, is equal to the distance of the Poles of the World from the Zenith, the Day is twenty and four Hours, and the Ar­tificial Day excresceth, and shoots out, into many Natural Days. 3. The Sun being in the same Parallel, he lightly toucheth, the border of the Horizon, and coming to it, she shines only with an half Orb. 4. They have but only one Solstice, in the Tropick of Cancer; for the other in the Tropick of Capricorn cannot be seen. But Analogically, and [...]n similitude there are six Solstices. Two high, when the Sun is in the Tropick of Cancer: for there, as well to the [...]outh, as to the North, the hight of [...]he Sun in the Meridian is highest, al­ [...]eit the Northern be greater than the [...]outhern: and four lowest, when the [...]he Sun toucheth lightly the Horizon. [...]. They have one Summer, and one [...]inter, but their Summer may be so [...]alled only Analogically: for these [...]laces of the Earth, are perpetually stiff [...]ith Snow and Yce. 6. They have [Page 84] four different Shadows, one from the East, one from the West, one from the South, and one from the North. Here are the Periscii. 7. The Gnomons, and stiles of their Dials, describes with their Points, Elliptical Figures.

CHAP. XXI. Of the Phenomena of the seventh and last Position.

1. THere are here no Stars, which either rise or set, but all of them are whirled about, equally distant from the Horizon. The Artick and Antartick Circles, are one and the same with the Horizon, and Equinoctial, which are now united. Understand this of the fixed Stars only; for the Pla­nets absolving their course, rise and set, in their appointed times. 2. The Ar­tificial Day is extended to half a Year; so is the Artificial Night, and therefore the quantity of the Natural Day, and [Page 85] the whole Year is one and the same. 3. When the Sun is in the Equinoctial, he shines only with half his Orb, and toucheth lightly the Horizon, and there he riseth and setteth only at those times. 4. No point of the Heavens, can be cal­led, either West, East, South or North, seing the Pole of the World doth not incline to any part of the Horizon, by which Inclination the four Points of the Universe, have their distinction. 5. They have only one Solstice, to wit, in Can­cer, but Analogically two other may be added, to wit, when the Sun is in the beginning of Aries, and Libra. 6. There is one Summer and one Winter: but their Summer is rather to be called a slender slaking of the Cold. They have one Winter, because the Sun is under their Horizon a whole half Year together. 7. The Gnomons of their Dials, describe with the extremity of the Shadow, upon an Horizontal Plain, perfect Circles.

FINIS.

Proteus Bound with Chains:

OR,

A Discovery of the Secrets of Nature, which are found in the Mercurial-Wea­ther-Glass, unfolding the Reasons, and Causes, why before Fair Weather the Quicksilver Ascends, and before Foul Weather, it falls down, and Descends.

A Subject not hitherto Treated of.

TOGETHER

With some brief Observes upon the Pa­risian Weather-Glass, and an Expla­nation of the Sealed Weather-Glass, and common Weather-Glass.

To all which is Added

The Theory of the Weather, according to the Perpendicular Weather-Glass.

By GEORGE SINCLAR, sometime Professor of Philosophy in the Colledge of GLASGOW.

Felix qui potuit rerum cognoscere causas.

Edinburgh, Printed by the Heir of Andrew Anderson, Printer to His most Sacred Majesty, Anno Dom. 1688.

Proteus bound with Chains: OR, A Discovery of the Secrets of Nature, which are found in the Mercurial Weather-Glass, &c.

THere are many excellent Questions to be Refol­ved, and Causes of the various Phenomena of Nature to be ren­dred, before a man can have knowledge to mount the Mercurial-Weather-Glass. Yet there are many, who rashly adven­ture, and bring upon that unerring and infallible Master-piece of Nature, the scandalous and odious Character of Fa­libility, either by raising the Mercury too high, or fixing it too low in the Cylindrical-Glass, both which Extreams [Page 4] must be cautiously shunned. For if it be not ordered according to the Authen­tick Observations of the Weather for many Years past, it cannot but err. And herein its infallibility and perfecti­on consists, to give the Theory of the Weather a just and determinate hight, according to long Observation, and by consequence the top of the Cylinder the same hight, none of which no ignorant person can do. The Questions to be resolved, are such as follow, 1. What sustains the Mercury in the Glass-Tube, whilst the Orifice is always downward, and open? 2. Why the Glass must ex­ceed in length, one and thirty Inch? 3. Why the Mercury falls not down, if it be shorter than twenty and eight? 4. Why the Mercury is carried up with violence to the top of the Glass-Tube, whilst the Orifice is raised above the surface of the stagnant Mercury? 5. Why as much Mercury in hight, is sustained in the wide Glass, as in the narrow? 6. Why, tho the Glass were in hight many Foot, yet the whole Mercury falls [Page 5] down to twenty and nine, or thirty Inch above the Cistern? 7. What fills up the space left empty behind? 8. Why the Mercury subsides by degrees, as the Weather-Glass is carried up some high Mountain, and why it rises again, as it is carried down? 9. Why a Glass of thirty six Foot high is required to make a Weather Glass with Water in it? 10. What's the reason, I do not find the weight of the Mercury within the Glass, whilst I poise it between my Fin­gers, and yet I find another weight ex­actly the weight of it? 11. What that other weight is? All these and many more are fully and clearly resolved in my Philosophical Experiments twenty years ago.

But there is a late Question, which troubleth all the Learned to resolve, which now I intend shortly to explain, viz. What's the reason, why the Quick­silver in the Weather-Glass creeps up before Fair Weather, and falls down before Foul Weather? For an answer to this considerable Question, it is to be [Page 4] [...] [Page 5] [...] [Page 6] observed, that in the foulest Weather, I have found the Quicksilver fall down to twenty and eight, and in the dryest, and fairest Weather, I have found it up at thirty and one Inch. From this ex­cellent Phenomenon only, it is called the Weather-Glass, Kat'exohen, by way of excellency: because before this alte­ration was found in it, it was called by the most part of Philosophers, the Torri­cellian Experiment.

For clearing the Question in hand, I suppose that in the Beginning, there went up a Damp from the Earth to wa­ter the whole face of the Ground. Mo­ses ( Gen. 2.) relates now the ordina­ry means appointed by God in Nature, for bringing forth of Herbs, Bushes, and Trees out of the Ground, viz. the Damp, which causeth the Rain, and moistneth the Earth, which Damp be­ing by the heat of the Sun rarified, a­scendeth to the middle Region of the Air, where by means of the coldness thereof, these Vapors are condensat, and thickned, and tur [...]d into a Cloud, and [Page 7] afterward are turned into Rain, and so fall down.

That there are such Damps and Va­pors, which ascend from the Earth, and Waters, cannot rationally be denyed; nay many Thousands and Millions of them ascend, which we do not see nor observe. I have seen in Frosty Morn­ings the mouths of Coal-sinks, and em­pty passages from waste Ground, where Coals have been digged out, Fumes and Vapors coming out so plentifully, as Fumes from a Salt-pan. Some do fitly compare this Earth to a Bag-pudding, taken out of a Boiling-pot, which sends forth Vapors in abundance. Likewise from the surfaces of standing and run­ning Water, what numbers may be seen in a warm Summers Evening. Nay from the Bodies of Men and Beasts, there is a perpetual Perspiration. But the finest and purest of all, are those which are exhaled from the Earth, and Waters. We see, that when the Sun is hot in Summer, the whole face of the Ground after Rain, covered over with Unduls, [Page 8] or little curled Waves, a small Gale of Wind being stirring, like unto the cur­led Waves of the Sea, Analogically. And so slender and pure are they, that whilst a man is among them, he cannot see them, but at a distance he may, look­ing alongs the face of the Ground. Likewise what multitudes of them may be seen alongs the surface of the Sea, a man standing at a considerable distance from the Coast. And so thick are they, that they have wonderfully lifted up, and magnified, much of the Land, and have made it appear, far otherwise than it was; nay, eclipsed whole Villages and Towns, and metamorphosed them into various shapes and forms, all which have come to pass, by reason of their multi­plicity and thickness. Now these Va­pors, flowing from the Earth and Wa­ters, are carried up to the middle Re­gion of the Air, where by process of time, they are condensat, and thickned, by the coldness thereof, and fall down in Rain.

But here it may be inquired, By [Page 9] what cause, [...]r power, are these Vapors carried up, seing they are Material things, and endued with weight? For answer, I must premit some few things, which do not ordinarly occur. First, That in all heavy Bodies, there is a twofold weight, one Specifical, the other Indi­vidual. The Specifical weight is found in Bodies, which differ by Nature, as Wood, and Stone, ballanced one with another, equal quantity with equal quan­tity. [...] Individual weight, is likewise found in the same Bodies, but after a different way and manner. For exam­ple, Stone is naturally, or specifically heavier than Wood, putting equal quan­tity against equal quantity; for a Cu­bical-foot of Stone, is heavier, than a Cubical-foot of Water. Bodies of the same Individual weight, or such as are weighed in a pair of Scales, as a Pound of Lead, and a Pound of Wool, are in­dividually of the same weight, but of different weight Specifically. Second­ly, There are two sorts of Ballances, the one Natural, the other Artificial. [Page 10] The Natural Ballance, is the Mercurial Weather-Glass, wherein the Mercury coun­terpoiseth the Air, and the Air the Mer­cury, both of them observing an equal Altitude, according to their natural weights: for since the Mercury is recko­ned 14000 times heavier than the Air, the pillar of the one must be 14000 times lower than the other; and so both are of the same hight, according to their Specifical weights. The Artificial Bal­lance, is that Mechanical Power, called the Libra. Thirdly, That one Body naturally lighter than another, may be­come of equal weight, or heavier, than that other. For example, the Vapors, which ascend are far lighter specifically, than the Air, yet they become heavier specifically, when contracted, and re­duced by a Cold, to a thicker habit, or consistency, and most of all when they are converted to Rain. But how shall it be known, that the Vapors are natu­rally lighter, than the Air? I answer, If it were possible to take an equal quan­tity of Vapors, with an equal quantity [Page 11] of Air, and weigh them in a Ballance, the Air would be heavier. We know that Oil is lighter than Water, for be­ing put under Water, it riseth to the Surface: so the Vapors go up thorow the Air, as Oil goeth up thorow the Water. Now I come to the Question in hand, and I affirm, that the Vapors are carried upward, not by the heat of the Sun, which is an vulgar error, but they being specifically, and naturally lighter, than the Air, are prest up by it, as Smoak, till they come so far up, as the pressure of the Air, is able to car­ry them. I shall make this evident, by the following Experiment. Let a Diver go down to the bottom of the Sea, with a Bottle of Oil in his Hand, and pour it out there, he shall find, that such is the pressure of the Water, it shall drive it all up to the Surface above. For as the Oil is naturally lighter than the Wa­ter, so these Vapors are naturally lighter than the Air. Now these Vapors, which are infinite in number, ascending from all the parts of the Earth, to the Atmo­sphere [Page 12] many Miles above the Clouds, causeth the Air here below press with greater weight, upon the stagnant Mer­cury, and so raiseth the Quicksilver in the Weather Glass, one Inch or two, and sometimes three: for it is not pos­sible, that the Air above, can be prest down, and burdened, with that new weight, and addition of Vapors ascend­ing, but the stagnant Mercury below must find the said pressure.

But how are these Vapors condensat and thickned together, and fall down in Rain▪ I shall do this, by a most evident, and clear example. We can­not more fitly compare these Vapors, ascending and descending again in Rain, than to an Alembick, or Distillater. For these Fumes being carried upward within the Pot, and meeting with a cold Receptacle (for the Pipe descending goeth ordinarly thorow a Vessel full of cold Water) they are presently reduced, to their first condition, and fall down in Liquor. So are the Vapors, which [Page 13] ascend from the Stomach to the cold Brain received and distilled.

But why should the falling down of the Rain cause the Quicksilver fall down, and why should the rising of the Vapors, cause the Quicksilver to rise? For clearing of this, it is to be adverted, that whilst the Mercury is up at one and thirty Inch, there is an equal ballance or weight between the weight of the Atmosphere and the weight of the Quicksilver, so that there cannot be the least weight subtracted from the pressure of the Atmosphere, but as much must be subtracted, from the hight of the Quicksilver: as by taking away one Ounce from this Scale of a Ballance, the other presently goeth down, or by ad­ding one Ounce to this Scale of a Bal­lance, the other Scale presently goeth up. Hence is it, that the pressure of the Atmosphere becomes less, by the falling down of the Vapors, and con­sequently the hight of the Quicksilver, must decresce also. And contrariwise (which clears the second part of the [Page 14] Question) whilst the Vapors are ascen­ding, and going up, the Atmosphere is more burdened, and by consequence the Quicksilver riseth, sometimes less, and sometimes more, sometimes one Inch, sometimes two or three.

But how comes it to pass, that the whole Air, or that great and vast bulk of it, can be in equal weight, with so small a portion of Quicksilver, granting the Air to be so heavy, as is commonly reported? I answer, It is not the Air according to its thickness, or bulk, which makes any coun­terballance with the Quicksilver, but it is the Air reckoned according to hight, because Fluid Bodies do not counter­poise one another, according to all their dimensions, but only according to Al­titude; this is only proper to Solid Bo­dies. For let never so much weight be added to the Air in thickness, itshall never make the least alteration in the Mercury. But if there be but the least addition made in hight, the Quicksilver presently knows it, by rising and falling accordingly. For by how many thou­sand [Page 15] times the Air is specifically lighter than Quicksilver, by so many thousand times is the pillar of Air, higher than the pillar of Quicksilver. And contra­riwise, by how many thousand times the Quicksilver is naturally heavier than the Air, by so many thousand times must the Cylinder of Quicksilver, be shorter than the Cylinder of Air, which sustains it. The proportion is ordinarly recko­ned as 1 to 14000. That is to say, one Cubick-Inch of Quicksilver counterpoi­seth 14000 Cubick-Inches of Air, both being put into a Ballance.

It is evident from this, and many other things, that there is a proportion observed in all the Works of Nature, as here between the hight of the Atmo­spere, and the hight of the Quicksilver: for all the Lords Works, are made in Weight, Measure, and Number. This truth is so evident in the Mathematical part of Learning, that there is no need of proof. And if this proportion be not observed in things Artificial, viz. by Architects and Builders of Houses, the [Page 16] whole Fabrick looks pitifully, and wants that face, and delicate aspect, it ought to have. And as the most wise Artist of the World, hath created all things in proportion one to another, so all the parts of his Holy Word, are in such a proportion one to another. For this we have Scripture, and Divine Autho­rity: for it is said, Whether we prophesie, let us prophesie according to the proportion of Faith. The Original word is, Ana­logia Pisteos, well rendered in our Vul­gar Language, the proportion of Faith, or Analogy of Faith, not as some, the Measure of Faith.

GOD is not tied to Numbers, yet nevertheless, he doth and disposeth his Works, by Number, Weight, and Mea­sure. It is observed, that after the go­ing up out of Egypt, GOD caused to be numbred all the Israelites, from the Age of twenty years and upward, ( Exod. 38. 26.) and there were found six hun­dred three thousand five hundred and fifty men. The year following, GOD commanded to make a second Review [Page 17] of the People, ( Numb. 1. 46.) but without comprising the Levites, which had been numbred the first time with the other Tribes. Notwithstanding this Subtraction, and the Casualities, which might have changed the number of the People, since the year foregoing, it is found that their number was yet justly and precisely six hundred three thousand five hundred and fifty men. In which is seen a proportion which GOD held in the multiplication of that People. There is also observed a Mystery in the exact number of the two and twenty thousand Levites, which were then recko­ned ( Numb. 3. 39.) For the rest, I contend not against the common opi­nion, touching the hundred fourty and four thousand of the seventh of the Re­velation, that they ought to be taken for an indefinite number, as well as the seven thousand which had not bowed the Knee to Baal. But it ought to be considered, why the Holy Ghost, who speaketh nothing superfluous, is not contented to have named the total sum of [Page 18] them, that were sealed in Israel, but al­so divideth it, in twelve times twelve thousand, distributed by equal portions among the twelve Tribes, every one of which is mentioned, the one after the other, with the expression of its parti­cular number: for this sheweth, that the number of the Elect, and the multitude of Believers, are measured by certain proportions, which are known to him, who is the Author. Certainly, the resemblance of the seventy Disciples of Christ, to the seventy Judges, which were substituted to Moses, and to the seventy Children, which Iacob had when he went down into Egypt, is a line of this admirable Symmetry, with the which God hath limited, and proportioned the Body of the Church.

Now this fortifieth that Maxime, that the number of the Elect cannot suffer addition, nor diminution: and that E­lection proceedeth not, from the Will of the Elect, but that of God, which prevented them. For it cannot be said, that all the Elect, from the beginning [Page 19] of the World to the end, have agreed toge­ther to make a Company composed pre­cisely of a number certain and regular.

But I return. It may be here inqui­red, Whether those Vapors, and Exha­lations go perpetually up from the Earth, or not? 'Tis probable, that they are alway ascending, tho insensibly to us, and as many of them in the Night, as in the Day-time. Nay, more (it seems) in extream Frost and Cold Weather, than at any other time; as we see in Green­land, where the greatest extremity of Cold is, there are infinite Treasures of Snow, which Snow could not fall down so plentifully, if there were not Vapors perpetually ascending. Next, after Rain, and the falling down of the Mer­cury to 28, or 29 Inch, I have found the ascent of it, in that same Night eight or ten Degrees, which could not hap­pen, unless there had been an addition of new weight to the Atmosphere. And this is observed, to be rather in the Winter, than in the Summer Season, espe­cially in calm Nights. I have observed, [Page 20] that the next Morning after Frost all the Night, the standing Waters in Furrows, which have remained many Days en­tire, dry up, and nothing remaining, but emptiness below a surface of thin white Y [...]e. This Water could not sink into the Ground, more that Night, than many others before; but the Frost coming on, and the Air becoming dry have turned all the Waters into Vapors, and so have been exhaled.

I would have it made more evident, how the greater pressure of the Atmo­spere by the weight of these Vapors make the Quicksilver rise in the Wea­ther-Glass? I answer, Take the Wea­ther-Glass, and place it within a dry Harbour, before the Water begin to flow. Then suppose the hight of the Mercury to be eight and twenty Inch. I say, when once the Water hath flowed, but three Foot and a half in hight, above the stagnant Mercury in the Cistern you will find the Mercury in the Weather-Glass three Inch higher. For as the growing of the Tide above the stagnant [Page 21] Mercury raiseth it higher, and higher in the Glass, so the ascending of the Va­pors loadneth the Atmosphere, more and more, and consequently it presseth with more weight upon the Mercury in the Cistern. And as the Vapors are turned into Rain, and the Mercury falls down; so by the ebbing of the Water, the three Inch of Mercury, falls down within the Weather-Glass.

It may be inquired, How far do these Vapors ascend? I answer, That Phi­losphers distinguish the Air into three Regions, the first, second, and third. But both Philosphers and Astronomers do vary exceedingly in determining the hight of any of them. I shall not cu­riously inquire, but shall speak a little to what concerns the present purpose. 'Tis probable, that these thin and light Vapors, which flow out of the Earth and Waters, go many Miles above the Clouds, where there is neither Wind nor Rain: for the pressure of the Air being powerful many Miles up, must carry the Vapors, so far up. But to de­termine [Page 22] particularly, it is not possible, only in general they ascend very far. Now it is evident, that the Atmosphere, is composed, and consists of such Va­pors being called Sphaera halituum, which no doubt, is of a considerable thickness, and hight. These Vapors, when they are once past the inferior Region of the Air, which will not exceed an English Mile, and a half, go up quickly, and are received by the Atmosphere, where they accresce to a considerable hight, perhaps 40 or 50 Mile above the Clouds, where by some extrinsick cause, as ex­tremity of Cold, they fall down from the Atmosphere, first as Mist or Dew, till they come to the lowest Region, where in a very short time, they cover the whole Heavens, tho never so clear before. How many times before Rain, will this be seen.

Besides, there is above the Atmosphere, that which Astronomers call the Dilu­culum and the Crepusculum, that is, both the Dawning of the Day, and the Twi­light in the Evening, the one beginning [Page 23] about two Hours before the Sun rise, and the other ending about two Hours after the Sun is gone down. For if that Crepusculum were not there, we should have no Light, until the Body of the Sun were above the Horizon, and should have no Light after the Body of the Sun is set. This Sphere is unalterable, and without accresce or decrease, but the Atmosphere is not so, by reason of the Vapors coming to it, and decreasing again. Next, the Refraction, which makes the Sun or Star to appear above the Horizon higher, than really it is, is caused by the Atmosphere. 'Tis ob­served by Shepherds, that if the Sun appear sooner above the Horizon, than ordinary, the Day following shall be Rainy. They see indeed the Image of the Sun, a little before he rise, which is caused by the Refraction, or thick Me­dium of the Vapors, which ly about the Horizon. For example, Let a man so fix his Eye, upon a wide Vessel, with an open mouth, with a piece of Money in the bottom, he shall not see it, till [Page 24] the Vessel be fill'd with Water. For Water being a thick Medium raiseth the Image of the Money, and brings it to the Eye by a broken and crooked Line, which is Radium refrangere, or rather refringere.

It may be further inquired, Why the Clouds are sustained, or what keeps them up from falling down? This is a considerable Question, and well wor­thy of a Divine Answer. The Lord says to Iob, Dost thou know the ballancing of the Clouds, the wondrous works of him who is perfect in Knowledge? The Clouds then are suspended, not miraculously, yet wonderfully by Natural Causes; for as a Ship is sustained from sinking by an even Ballance with the Water, so are the Clouds keeped up, by an even and equal Ballance with the pressure of the Air, which really sustains them. If they be light and thin, they go further up, but if they be heavy and black, they come nearer to the Earth, but are still in an equal Ballance, with the pressure of the Air. And as the Loadned Ship [Page 25] goeth further down in the Water, than the Ship, that's not burdened; so do the black and heavy Clouds swim lower, than the light and white Clouds. But when there is a great convocation of Clouds together in one place, each one presseth upon another, and so like Ho­ney-Combs they distil their Drops up­on the Earth. Note, That the greatest Ship in Europe, with all her Furniture for War, is but the just and exact weight of the Water, thrust out of its place by the Ships Water-draught.

It may be yet inquired, How far are these Clouds from the Earth, which send down the Rain? I answer, The surest way to know, is by the Thunder. Ob­serve then, how many Seconds of Time, do pass, between the first seeing of the Glance, and the hearing of the Crack. If the Noise be straight up, five or six will pass, which make an English Mile. In Mountainous Ground, which lyeth higher, three at the most will interveen, about five hundred pass. To know ex­actly a Second of Time, whereof 3600 [Page 26] make an Hour, follow this method. Take a small Chord of thirty and seven Inch and a half exactly. To which ap­pend a Lead-bullet of seven or eight Ounce. Hang it so, that it may swing to and fro of its own accord. Each one of these Swings are a Second of Time.

But may it not be affirmed, that the greater pressure of the Air, which rais­eth the Quicksilver, is caused by the weight of the Clouds, which swim above us: and that the falling down of the Quicksilver is caused by the dissolution of these Clouds into Rain? I answer, This cannot be: for when the Heavens are most serene and clear, the Mercury is furthest up; and when the Heavens, are nubilous, and covered with Clouds, the Mercury many a time is furthest down.

It may be inquired, Whether the cracking of Thunder, maketh any alte­ration upon the Weather-Glass? I an­swer, There are three things to be con­sidered in Thunder, First, The Light­ning. Secondly, The Crack. Third­ly, [Page 27] The Thunder-bolt: which three are lively represented to us by the shooting of a Cannon; for the Fire coming out of the Muzzle, represents the Light­ning; the Report, represents the Crack; and the Bullet, the Thunder-bolt. But there is a more lively representation of Thunder, in Aurum fulminans, which like the Thunder-bolt carrieth its stroak downward, three Grains of which, tho never so little made hot, takes Fire, and gives a greater Report, than two Ounces of Gun-powder, so stupendious is it. But there is nothing here, which can make any alteration upon the Wea­ther▪Glass.

It may be inquired, If the Winds make any alteration upon it? I answer, Winds are nothing but Air agitated; nor Tempests, but Air-floods, or vio­lent Agitations of the Air. These do really influence the Weather-Glass, not only in causing the Quicksilver subside, and fall down, but in causing the top of the Mercury tremble, and make some visible reciprocations up and down, e­specially, [Page 28] when the Wind blows very high. Next, Winds which come from the South and South-west, by reason of much moistness, which they bring alongs with them, influenceth the Quicksilver much indeed. But Northerly Winds, which are more drying, have less influ­ence. Nay Easterly and North▪east Winds even with Rain, keep up the Mercury, and suffers it not to fall down so far, as other Winds. Because such Winds come from the Great Continent, bringing with them many Earthly Par­ticles, and Atoms, which being dry, have not that influence upon it, as moist Winds from the South and West.

It may be inquired, If the Weather-Glass doth foretell Winds, as it doth Rain? I answer, It doth not so much foretell Winds, as it is actually influen­ced by them. Yet, if a man were a diligent Observer of the Winds, before they blow, and took narrow inspection of the Weather-Glass, he would surely foresee them approaching, by some alte­ration or other in it.

[Page 29]It may be inquired, Whether Mist or Fog, doth affect the Weather-Glass? I Answer, Yes, for I have observed, when the Mercury has been up at Fair, the falling down of a Fog, hath brought it down three or four Degrees.

It may be inquired, When the Mer­cury i [...] at the highest Station, in the fairest Weather, as above Long Fair, how many Days doth it prognostick Rain, before it come▪ I Answer, When it first begins to alter, it must fall down to Long Fair, half an Inch; next to Fair, another half Inch. Thirdly, To Changeable, as much: And lastly, To Rain. This Motion is slow, and therefore it foretells, sometimes three Days, sometimes four, sometimes less▪ But this is sure, it cannot fall down in one Day so much bounds, nor in two, neither in three. I have seen it fall down from Long Fair to Fair, and then halt, by reason of some stirring Winds, or by reason, of some small change of Weather, in some County near hand. When it's far up, as at Long Fair, or [Page 30] above it, it is next to impossible, that either Wind or Rain can be.

Some, who are not acquaint with the Weather-Glass judge it erring, when they see the Mercury at Rain, and yet no Rain. I confess it may be so, if it be not rightly adjusted, at the first set­ting up; but if it be set, according to Art, the Mercury cannot be at Rain, but there must be Rain, either here, or some place near hand.

It may be inquired, If Snow and Hail have the same effects upon the Weather-Glass, which Rain have? I answer, Yes; for they are both from the same cause, namely moist Vapors. I have [...]s the next adjacent Hills covered with Snow, when there was neither Rain nor Snow in the Valley Countrey, and the Mercury down at Rain, tho it had been always up before the Snow fell. And many times it is found, that Rain falling in the next Shires, or Counties, tho none here, have made the Quick­silver fall down to Rain. The last year 1687, in November, I have seen the [Page 31] Quicksilver, below Much Rain, and yet the Days going before, or following, have been pretty fair. But the Wea­ther, was under a strong disposition, and inclination to be Tempestuous and Stormy, which soon followed. 'Tis ob­servable, that the Quicksilver, is never so high in the Weather-Glass, as about the hinder end of the Month of October, or rather in the Winter Season. In Rainy Years, I have not seen the Mer­cury further up than Fair, and that sel­dom.

Might the Weather-Glass be useful in Ships? I answer, Yes; but the com­motion of the Ship, (you say) renders it useless. I answer, it might be so su­spended, that it might hang always per­pendicular. And tho this were not, yet the Nature of it is such, that it can recline without hurt, as much as the Ship can [...]ly, either to Starboord, or Larboord, and fall right again, when the Helm is righted. In a word, what­ever advantage a man might have by it, [Page 32] in his Chamber, he may have as much, by having it in his Cabin.

There is a person of Honour, and great Learning, who hath written late­ly in Natural Philosophy, and among o­ther things, hath not omitted to shew the reason of this marvellous Phenome­non, whereof I have been Treating. He toucheth it briefly in 9 or 10 Lines, and says, Id autem mirum satis videtur, &c. 'Tis a strange thing (says he) that in Rainy and Windy Weather, when the Air seems to be heaviest, yet the Mer­cury is furthest down. The reason (says he) is taken from the temperament of the Air, where the Clouds are; for when the Clouds are grosser, tho much elevated, they intercept the Rays of the Sun, and are thereby melted, and tur­ned into Rain. And the Air being eased of the burden of these Clouds, and being rarified above, by the Sun-beams, is becomes lighter, and so bears less down the surface of the stagnant Mercury in the Cistern. But when the Air is nubi­lous and Cloudy, the weight of the Air, [Page 33] is augmented, by the weight of the Clouds, which make it press with greater weight upon the stagnant Mercury in the Cistern.

I dare not oppose any thing to the Opinion, of such an eminent man, tho I might, he being a hundred Stages be­yond many. Yet there are not some wanting, who male-apartly set at nought his Philosophical System, as insufficient both for Matter, and Form; whereas among all the Learned Abroad, his Wri­tings are held in great Estimation.

There is one of the Professors of Philosophy at Aberdeen, whose publick Theses the last Year, came to my view: yet I shall adventure to say something anent them. The Author, (whom I have not the favour to know) seems to be well acquaint with the new Philo­sophy, and a good Schollar. He con­futes rationally Malebranch, and Spinosa, two wild Philosophers. He seems to be a Cartesian in his Philosophy, yet affirms that the Demonstration (as he calls it) of God's Existence, by the Idaea, being [Page 34] abstract and Metaphysical, goeth far be­yond the capacity of the Vulgar, and therefore being compell'd by Reason, he averreth, that the Apostle Paul rea­sons far better in the first to the Ro­mans.

He speaks honourably of the late Lord President in confuting some of his Doctrine, for which he deserveth more thanks for his good Estimation of him, than for the strength of his Reasonings against him. He hopes the Lord Stair, will hold him excused, if he do not ac­quiesce to his Decisions. This seems to be jeastingly spoken. Casting my Eye further thorow, I found somewhat anent the Causes of Winds, Tempests, and Rain, and the reason why the Atmo­sphere, is sometimes lighter, and some­times heavier. But he hath not touch­ed the Nail upon the Head.

Some Notes upon the Parisian Weather-Glass.

THere is a New Invention of a Weather-Glass, which cometh from Paris (facile est inventis addere,) set in a curious gilded Frame, more specious to behold, than profitable and useful. It is lyable to se­veral Abatements. The first makes it a dumb Weather-Glass, wanting the whole Theory of the Weather, so that when a man looks to it, he knows not whe­ther it shall be Fair or Foul. A man seeth indeed the sides of the Frame, di­vided by French Measure into Inches and half Inches; but these Measures have no signification of the Weather. When a man looks upon it in the Mor­ning, he sees the Tinctured Liquor at such a hight; and in the Afternoon, he [Page 36] observes again, and finds it higher or lower. This is all it signifieth. And if perhaps he be informed that in Fair Weather, the Liquor descends, and in Foul Weather it ascends, then he may conclude, observing it further down than it was, that it is probable to be Fair.

The second Abatement is, that there are two Oval-Glasses, which rather ought to be Cylindrical. Now unless there be a just and exact measure in hight, between the top of the one Oval-Glass, and the bottom of the other, it cannot be un-erring, or between the middle of the one, and the middle of the other. Because the Mercury can­not raise the Liquor in the right side, by equal portions, since the rising of it depends essentially upon the falling down of the Mercury from the left Oval-Glass. For the Glass being in form of a Pullets Egg, more Mercury falls down, whilst it is terminate about the middle, being there wider, than whilst the Mercury, is near either of the ex­treams, [Page 37] which are narrower. And I believe the Contriver hath foreseen this.

The third Abatement is, that the Tinctured Liquor is subject to Corrup­tion, the Orifice of the Glass being open, suffering Evaporation, by which means, the whole Contrivance is ren­dred useless.

The fourth Abatement is, that the Orifice of the Glass, upon the left Hand, must be Hermetically Sealed, which few or none can do.

The fifth Abatement is, if it be once Mounted, and set a going, it cannot be well Dismounted, for the end which is Hermetically Sealed, must be opened, and cannot be well Sealed again.

Lastly, The Glass is brought Home from Abroad, not without hazard of breaking, the Glasses being very small and slender.

But there are none of these Difficul­ties found in the Perpendicular Glass. For it may be set up, and dismounted, as oft as you please, and transported from one place to another. And the [Page 38] excellency of it is, that it sets it self; for whatever weight of Mercury it once takes, the same will suffice it for ever. And which is marvellous, the Mercury falls down alway according to the Na­ture of the Weather, and there halts, whether it be Fair, or Foul.

There is a second sort of Weather-Glass much in use, called the Sealed Weather-Glass, whose use is only to shew the Heat and Coldness of the Air. It hath a round Glass below, about two Inch in Diameter, and a Stem going up from it, about a Foot and a half in length, but slender and narrow within. This Glass is filled with the finest Spirit of Wine, three or four times distilled, so in effect, being full of fiery Spirits, the least Heat or Warmness in the Air, rarifieth it, and the least Coldness con­tracteth it. When the Ball is once full, and the Stem too, the open Orifice a­bove is Hermetically Sealed, and com­ing to the cold Air, from the warm place it was in, the Liquor creeps down towards the Ball, and by this means, it [Page 39] demonstrats by its creeping up, the warm­ness of the Air, and by creeping down it shews the Degrees of Cold. It is Her­metically Sealed, that the outward▪ Air, may have no influence upon it. It is set in a curious gilded Frame, with the several Degrees of Heat and Cold affix­ed to it. They come from Paris, and London, not without hazard of breaking by the way.

There is a third sort, specially diffe­rent from the rest, called the Water Weather-Glass. It hath a round Head above, with a long Stem going down from it, and the Mouth below remain­ing open, is drown'd among Tinctured Water. To set it a going, they use to warm the Head, and Body of it, at the Fire, and then to thrust the open end among the Liquor in the Cistern. When the heat begins to abate in the top, the Air within, begins to contra [...] it self, and so the Water follows up, and hangs about the middle of the Stem. This in cold Weather creeps up, and in warm Weather creeps down. It creeps up for [Page 40] fear of Vacuity, as was maintained long since, before the pressure of the Air was known by the Torricellian Experiment. This Weather-Glass was esteemed infal­lible; but now it is known to be most fallacious, and uncertain. The reason is, because it is acted and moved, not only with Heat and Cold, but with the greater and lesser pressure of the Air. If it be demanded, how shall I know, whether it be the coldness of the Air, or the greater pressure of the Air, which causeth the Water to ascend: and whe­ther it be, the warmness of the Air, or the Iesser pressure of the Air which cau­seth the Water to descend? I answer, It is difficult to know; for both do some­time concur, that is, the weight and greater pressure of the Air, and the coldness too. And sometime the lesser pressure of the Air with warmness, make the Water fall down. And sometime the greater pressure of the Air raiseth the Water, without any addition of Cold: And sometimes the addition of Cold, without any alteration in the Air, as to [Page 41] more weight, will raise it. And tho by this means it be fallacious, yet many notable Phenomena do appear from it. By the help of this, and the Mercurial-Weather-Glass, and the Sealed one, and by the help of the Hygroscope, which marvellously shews the least alteration in the Air, as to Moisture and Dryness, and by contemplating the Heavens, the Sky and the Clouds, and considering the Winds, how they blow, and the va­rious Aspects of the Planets one to ano­ther, (as Star-gazers do affirm) men might come to foretell the Weather particularly.

The Theory of the Weather, ac­cording to the Mercurial-Weather-Glass.

THE Theory of the Weather, is either Ingraven upon Brass-Plates tichtly polished, or up­on a piece of Lombard-paper, wrought in the Taliduse-press. The Brass, or the Paper, is divided into Six half Inches; and every half Inch into Five Degrees; or every whole Inch in­to Ten equal parts. I call the upmost Station, Long Fair; the second half an Inch under it, Fair: the third, Change­able: the fourth, Rain: the fifth, Much Rain: the sixth, Storm [...]; and if you please to add the seventh, call it Tem­pests. These six or seven, contain the whole Alterations, which use to be in the Weather. When the top of the [Page 43] Quicksilver is at Long Fair, it toucheth exactly the Line under it. If it fall down, it is said to be one Degree under Long Fair, or two or three, according­ly as it falls down, till the top be at the Line under Fair, and then it is Fair Weather, and so of the rest of the Sta­tions. It may be asked, At what hight, must Long Fair be affixed? I answer, The Situation of the place must be con­sidered, and the Climat under which we live: for a Glass appropriated to this Parallel, will not serve in the Braes of Athol, or Annandale. And if there be not a just, and exact hight, to a Hairs breadth, of all the Stations from below, it cannot be un-erring. The several Sta­tions are found out, not by Algebra, or any Mathematical Demonstration, but by many years Observations. Who­soever taketh upon him to mount a Weather-Glass, without the knowledge of these Praecognita, he plays but the Fool.

There are many other things necessa­ry to be known, which every Fallow, [Page 44] which hath no more in his Scull, but a Bag-pudding in stead of Brains, is not capable to understand.

I shall briefly run thorow the seve­ral Stations, with some Observes upon each one of them. In the first and up­most, is Long Fair, or most pleasant Weather. I have seen the Quicksilver sometimes above it, yet seldom doth this fall out, but in extraordinary Sea­sons. The Mercury being at this hight, it is next to impossible, either to be Wind or Rain. Nothing for several Days, but settled calm Weather. Some­time the Heavens are covered with dry and gray Clouds, but not the least appearance of Rain.

The second [...]tation, half an Inch lower, is Fair. The Mercury being here, I have observed a small Showre of Rain to fall, from the lowest Region of the Air, as a th [...]ck Dew or Mist, but immediatly after, the Day became Clear and Fair. The whole year 1686 al­most, it was a rare thing to see the Mer­cury up at Fair, but frequently below [Page 45] Rain, and Changeable, because of the frequent Rains, which fell out that year. And which is observable, all that Summer, the Hygroscope went not once about, whereas in dry Summers, it goeth twice about, sometimes more and sometimes less.

The third Station half an Inch lower, is Changeable. That is, sometimes Fair, sometimes Foul, sometimes Frost, some­times Thaw, sometimes Sleet, and some­times Snow, sometimes Wind, and some­times Calm.

The fourth Station is Rain, not actu­ally Rain, but a stormy inclination in the Air to be Rain, and sometimes Rain. Nay, sometimes the whole Day will be Fair. But still the Rain is ap­proaching, or hath been Rain, either here, or some place about.

The fifth Station is Much Rain, the worst of Weather almost, as in the Summer, or Winter Season, when Rain is accompa­nied with stormy South-west Winds, or westerly Winds. This last October, or November, I have seen the Mercury be­low [Page 46] this Station, and yet no Rain in the mean time, nor all the Day, but the Sky black, and tempestuous, thick Clouds lying about the Horizon. Above Fife, great Heaps of them: some like Castles and Towers, others like ragged Rocks, hanging over each one another. All of them fore-runners of Rain.

The sixth Station, Stormy, extraordi­nary Foul Weather.

In the last place, I have subjoyned Tempests, or Hirricano's, which do not fall out in this Countrey. If it be ask­ed, Why doth not the Mercury fall down to Tempests? And why doth it not go half an Inch above Long Fair? I answer, There are here two Tropicks, namely Storms, the nethermost, and Long Fair the upmost. Above this, the Air is not able to press, except some few De­grees. And at Storms the pressure is least. The length of the Tropicks then, are about three Inch.

General Rules. The further the Mer­cury goeth up, the Weather inclines to be the Fairer, and the further it falls [Page 47] down, it inclines to be the Fouler. Se­condly, When the Mercury is highest, Fair Weather seems to be universal; when it is lowest, Foul Weather seems to be universal. Thirdly, It is not so much Foul Weather actually, which in­fluenceth the Mercury, as it is the Dis­position and Inclination of the Weather to be Foul: so that the Mercury will be many times at Rain, when it is not actu­ally Raining, which is wanting when the Quicksilver, is at Fair, or Long Fair. Fourthly, Not only Foul Weather in this County or Shire, maketh the Mer­cury fall down, but Foul Weather, in the next adjacent County, tho there be none here: as the Weather-Glass at Edinburgh, will be altered, with Rain in Tweeddale, or in Lammer-moor. And as it shews the Nature of the Weather, so it predicts and foretells, sometimes a Day, sometimes two or three, if so be the Mercury hath been far up. But if it hath been only at Changeable, or be­low Fair, it predicts some few Hours, before it be Rain, by falling down a [Page 48] Degree, two or three, or four. When it is a falling down, the top of the Mer­cury is flat and level, but when it is a rising, it is somewhat round.

'Tis said, that the Ladies, and Gentle­women at London do Apparel themselves in the Morning by the Weather-Glass. Whatever be in this, 'tis certain, that when a man riseth in the Morning, he may know infallibly, what sort of Wea­ther will fall out ere Night.

It is most useful for the Husband-man, both in Seed-time, and Harvest, and for winning of Hay. It is useful for taking a Journey, for when I see the Mercury up at Fair, or Long Fair, I may be confident, there shall be no Rain for eight or ten Days, chiefly when it's up at Long Fair.

There are many other uses, for which it is profitable, which are needless here to repeat. It is always infallible, because guided by God in Nature, tho to our apprehension it seems to err. There are so many Changes, and Alterations in the Air, that a particular Rule cannot [Page 49] be assigned for each one of them. But the general Observations which are affix­ed, are sure. If any man would find out all these Intricacies, he must dili­gently observe, the Changes, and Quar­ters of the Moon, and the several Aspects of the Planets, and the Winds how they blow, comparing them with the Changes and Alterations of the Weather-Glass. Neither can it be subject to Corruption, tho it stand an hundred year. The Glass cannot fail, neither the Quick­silver, which are incorruptible by Na­ture. Neither can the Frame decay, for many years, being made of Oak.

FINIS.

Postscript.
To Buoy up a Ship, of any Burden, from the Ground of the Sea.

THE Art of Diving hath not been much known, but of late; for it de­pends essentially upon the knowledge of the pressure of Fluid Bo­dies, which knowledge hath not been further known to the generality of Learned Men, than by name: tho some ignorantly have averred, that the [Page 2] Hydrostaticks, is a Science long ago perfected. Among the first, who have essayed in this Nation, was the late Marquess of Argile, who having obtain­ed a Patent from the King, of one of the Spanish Armado, which was sunk in the Isle of Mull, anno 1588, employed Iames Colquhoun of Glasgow, a man of singular knowledge, and skill, in all Mechanical Arts and Sciences. This man, not know­ing the Diving Bell, went down several times, the Air from above, being com­municated to his Lungs, by a long Pipe of Leather. He only viewed, and sur­veyed the Ship, but I suppose buoy'd nothing up. About the year 1664, when this Art became more perfected, and was advanced, by the Practice, and Invention, of Learned Men. The late Lord Argile did employ a most ingeni­ous Gentleman, the Laird of Melgim, who went down with a Diving Bell, and made a further inquiry. After some pains, and labour, he buoy'd up three Guns, one of Iron, judging it to be of some other Mettal, one of Copper, and [Page 3] one of Brass, about eight Foot long a­peice, and eight Inches of Diameter. The third Essay was made by the late Earl of Argile himself, several years af­ter, who did more. There was one Captain Smith, who undertook after that, yet more, who thought himself so sure of the Spanish Gold, that he would not suffer a Carpenter with himself: but this Interprize turned to nought. To effectuate the Proposal, I shall offer these six Propositions, which with small pains may be made evident, from Hy­drostatical Principles; and next infer some Conclusions, needful for the de­sign in hand.

First, The whole Ship, with all its Loadning, is the just and precise weight, of as much Water, as the lower part of the Hull expells, or is expelled by the Ships Water-draught.

Secondly, When the Ship becomes heavier than the said quantity of Water, it sinks.

Thirdly, Water doth not weigh in Water. This is evident, for when a [Page 4] man pulls a Bucket full of Water from the bottom of a Well, he finds no weight thereof, till it come to the Surface.

Fourthly, Nothing lighter in specie than Water, or of the same weight with Water, can sink. Hence, neither Tim­ber, Wine, Bear, nor Oil, can tarry at the Sea Ground, but must be buoyed up of necessity.

Fifthly, By how much, the whole Timber of the Ship, is lighter in specie, than as much Water equal to it in bulk, by so much is it the more able to buoy up. Imagine, the whole Timber of the Ship, reduced to a Cube of so many Foot, and a Cube of Water given of the same quantity. Now I say, as ma­ny Pounds, as this Cube of Water, is heavier, than that of Timber, so many Pounds of Iron, Lead or Stone, will the Ship buoy up, or support, even tho full of Water.

Sixthly, A heavy Body, as Iron, Lead or Stone, weighs as much less in Water, than in Air, as the quantity of Water it expells. A Square Foot of Lead, which [Page 5] I suppose weighs in the Air 728 Pound, weighs but 672 Pound in the Water, less by 56, the weight of a Square Foot of Water.

From these Propositions, I infer, that when a Ship is to be buoy'd up from the Ground of the Sea, nothing of her weighs, save her Ballast. By Ballast, I understand, taking the word largely, every thing in the Ship, heavier in spe­cie, than Water, as Guns, Ankers, Bul­lets of Iron, and Lead, Iron-bolts, Nails, and all manner of Iron-work. Next, That the whole weight of the Ballast, doth not preponderate or weigh down. Lastly, That the Timber of the Ship, and all things in it, lighter in spe­cie, than Water, concur for buoying up the Ballast.

The best expedient for raising of Ships entirely, are Arks of Wood, ap­plyed either to the sides of the Ship without, or just above the Orlop. These Arks must be so close, on all sides, that neither Air, nor Water, can pass. The Ark, to describe it more particularly, [Page 4] [...] [Page 5] [...] [Page 6] must have four Sides, and a Cover a­bove, but open compleatly below. At every Corner, next to the Mouth, must be fixed, a strong Iron-Ring. Four likewise above, that is, one in each Cor­ner, answering to the four below, which are for fixing a second Ark above the first, if need be. If the Ship, which is to be raised, be twenty Foot over, make your Ark twenty Foot wide, and as much in hight. Bring it just over the place, where the Ship lyeth, and filling it with Water, that it may sink without difficulty, thrust it down, till it come just above the Orlop, and fasten it with­in five or six Foot of the same, with Ropes passing thorow the four Rings, and the Beams or Balks of the Ship. The Arks being thus fastned to the Ship, by a Diver, the next work is to beget a power, or force within it, which shall be able to buoy up the Ship from the Ground of the Sea. This may be done, either by sending down Buckets full of Air, with their Mouth foremost, one after another, from the Surface of the [Page 7] Water, and then cause a Diver receive them, and thrusting them somewhat with­in the Mouth of the Ark, turn up the Orifice, by which means, the whole Air in it, shall ascend up thorow the Water of the Ark, and rest above, next to the top. This Device being often repeat­ed, will at last expell, the whole VVa­ter of the Ark, and fill it compleatly with Air. This is so sure an Experiment, that none needs to call it in question. Or by communicating Air to the Ark from above, by the help of a pair of large Bel­lows, and long Pipes of Leather, going down within the Mouth of the Ark. Or thirdly, By the multiplication of Blad­ders full of VVind, filling the Ark within, which may be done more easily. The Ark being oncefull of Air, will have a considerable pull with it, which is more, and less, according to the dimen­sions thereof. For knowing this, you must consider, that whatever t [...]e dimen­sions of the Ark are, it will buoy up, as much weight as the VVater weighs, which fills it. I [...] then, the Ark be twen­ty [Page 8] Foot wide, and as much in hight, it must contain eight thousand Square Foot of Water; and since every Square Foot of Water thereof weighs fifty six pound Trois, the whole must be 448000. An Ark then of twenty Foot Square, will buoy up, four hundred and fourty eight thousand pound weight, the weight of 58 Cannons Royal, each one whereof, I suppose weighs 8000 pound. Or the weight of 74 Demi-cannons, or the weight of 97 Culverings: or of 149 De­mi-culverings: or of 298 Sakers, each one of this sort weighing 1500 pound. Or lastly, the weight of 250 Tun of Wine, reckoning four Hogsheads to a Tun, and each one of these weighing 448 pound.

If you fasten a second Ark above the first, by the help of the Rings upon the top, which I mentioned, both will buoy up together 896000 pound, the weight of 112 Cannons Royal. But if your Ark be 30 Foot in all its dimensi­ons, it must contain twenty and seven thousand Square Foot of Water, which [Page 9] will weigh, one million, five hundred and twelve thousand pound weight of the weight of 189 Cannons Royal, or the burden of 252 Demi-cannons, which is the weight of 844 Tun of Wine. But supposing the Ark to be more in quan­tity, the one way than the other, that is 40 Footlong, it shall be able to buoy up, two million and sixteen thousand pound, the weight of 252 Cannons Royal, or the weight of 1125 Tun of Wine, or Water.

If the Arks be applyed to the sides of the Ship, you must fix, as many upon the one side, as upon the other, which need not be so large, as those which are fastned upon the Orlop. I shall sup­pose, that upon each side, there are four Arks, each one 10 Foot Square. If this be, every single Ark, must con­tain 1000 Square Foot of Water, which will weigh fifty six thousand pound. All of them together, therefore must buoy up 448000 pound weight, the bur­den of 56 Cannons Royal.

To know, how to proportion the [Page 10] quantity of your Ark, to the burden of the Ship, which is the great secret, follow this Method. Consider first, that neither the Timber of the Ship, nor the Water which is in her, nor any other thing, which is lighter in specie than Wa­ter, (that is, any thing which floats upon the Surface) or of the same weight, with it, preponderats, or weighs down, but only what is heavier in specie, than Water, as Guns, Ankers, Iron-bolts, Iron-nails, and such like, the just quan­tity, or very near, may be found. Cal­culate then, as near as you can, and supposing the weight of all this Ballast, to be about 448000 pound; you must next consider, what the dimensions of the Ark, must be, which is able to buoy up so much weight, which may be found out thus. Divide the just account of your Ballast by 56, and the Cubique Root of the Product, gives you the just dimensions of the Ark. For example, Divide 448000 by 56, and you will find 8000, the Cubique Root whereof is 20, the quantity of your Ark within.

[Page 11]If you judge▪ it more convenient to apply lesser Arks, namely to the sides of the Ship, ye may have eight, by divid­ing this into so many parts, four for each side, and every single Ark 10 Foot Square, which are equivalent. Remem­ber, that tho the whole Ballast, weigh 448000 pound, yet this whole weight is not to be buoy'd up by the Ark, seing heavy Bodies weigh less in Water, than in Air, according to the sixth Proposi­tion.

As for fastening the Arks, either to the sides of the Ship, or just above the Orlop, several ways may be thought upon, which I leave to the Invention of others, who are skilful in building of Ships. Let it suffice, that I have made it probable, if not evident with Rea­son, that the greatest Ship may be buoy'd entirely up from the ground of the Sea, which was the thing to be demonstrat­ed.

If it be Objected, That the strong pressure of the Water, will put the Ark in hazard of bursting, when its full of [Page 12] Air. I answer, There is here not so much hazard, as every one may believe. The Reason is, because the pressure within the Ark, is very near equal, to the pressure from without. This I add, because the top of the Ark within, is more prest up by the Air within, than it is prest down with the Water with­out. The pressure upon the sides, is more uniform, and so there is the less ha­zard there. In a word, if the Ark be able to support, as much VVater, as fills it, without bursting, it shall go down thorow the deepest VVater imaginable without trouble. That is, hang it by Ropes in the Air, full of VVater. If the bottom be able to support this weight, there shall be no hazard of bursting, when it's full of Air within the deepest VVater.

From this unequal pressure, which the top of the Ark suffers, it follows of ne­cessity, that if there be any Rift, or Leck in it, the whole Air will go out by degrees, and so render the Ark use­less. I answer, this endeavour, which [Page 13] the Air within, hath to be out, is just the same, with that, which the VVater within, hath to be out, when the Ark is full, and hung in the Air with Ropes. If Art can cure the one, it may find a remedy for the other also. But I leave this to such as are skilful in Calking of Ships.

Tho I seem to insinuate, that the Arks must be Cubical or Foursquare in their form, yet there is no necessity for that; for they may be made under what fashion or form you please, provided they con­tain, as much Air as will be sufficient to raise the Vessel. And though I mention Arks of 20 or 30 Foot Square, which will go near to buoy up the greatest Ships, as Men of VVar; yet for ordina­ry Vessels, Arks of far less size will suf­fice.

Some may imagine, that a Ship sunk (for example) with Coal, is as difficult to buoy up, as to raise her out of a dry Harbor. But this cannot be, since a pound of Coal, will not weigh three or four Ounce in the VVater. A Ship [Page] loadned with VVine or Oyl, weighs nothing at all in the VVater, but may be very easily buoy'd up, if the Ballast be considered, as I said. Many Ships have been buoy'd up entirely, by thrust­ing down empty Hogsheads, and putting them below the Deck. But here oc­curs a difficulty, if the Water exceed eight or nine Fathom, the strong pressure of it crusheth the sides of the Hogshead together. But here is a soveraign cure against that trouble. Bore a small Hole in any part of the Vessel, where you please: for the Water entering, brings the Air within, to press equally with the Water without.

Tho this Invention, may seem diffi­cult to some, to be made practicable, yet to such who are intelligent, and know well the Principles of the Hydro­staticks, it appears plain and easie. But the very Speculation of it wants not its own pleasure, being founded upon infallible and sure Conclusions, drawn from the surest grounds in Nature.

‘Labor improbus omnia vincit.’

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