TO prove this only two Axioms, or moral Truths (which will need no probation) are required to be granted, by which the Matters of Fact evident in the Case may be examined.

• Axiom. 1. That the Heat of the Sun being allowed to be the common Cause of drawing, and consequently of cockling and cracking a Lead-Covering, the Beams thereof, which fall with equal force upon an unequal Body (such as a Sheet of Cast-Lead is) must draw the thinner and weaker parts more than the thicker and stronger.
• Axiom. 2. That if a Plumber, or at least-wise two of the Chief Master-Plumbers in London, joining together, shall (upon a Wager, or Tryal of Skill, wherein their Interest is highly concerned) undertake to cast Sheets of Lead, not thinner throughout the whole Sheet, than the Size required, and very little thicker in any place, they will cast as well, and as near equality, and the Size given as they can; and that the Sheets cast by them in such a Tryal, or at least in two such Tryals, ought to be taken for the greatest certainty, Standard, and best Casting any Plumber can pretend to; or at least-wise that such Casting is much better than what any Customer in the common course of their Trade can expect from them. This being granted.

From the First Axiome it follows, That if the Plumber could cast exactly equal to the Thinner parts of his Sheet, his Cast-Lead would make a better Co­vering than to be thicker in one place than in another; for that the thicker and stronger parts resisting the Sun-beams more than the thinner and weaker, those parts must stay behind whilst the weaker move; which Motion by degrees cockles and cracks the Sheet; whereas if the Sheet were exactly equal as the Mill'd-Lead is, it would by the equal force falling thereon, move or stay equally as the Mill'd-Lead does, where no other Cause or Accident occurs: Here note al­so, that this excess of thickness in some places, is not only unnecessarily paid for, but it helps forward the ruin of the rest.

Mill'd-Lead Better.Wherefore Milll'd-Lead, which is exactly equal, tho no thicker than the thinner parts of a Cast-Sheet, must be allowed to be a better, and more durable Covering than Cast-Lead.

Divers other Tryals of other kinds were also since made by direction of the present Navy-Board, with which they being further satisfied, contracted for the Mill'd-Lead in general, for all services of Their Majesties Yards; declaring in their Instructions to the Officers, That they had (amongst other Faults) found up­on several Tryals made, that the Cast-Lead was so unequal and uncertain, they ould not have what they demanded, nor depend thereupon for Their Majesties Service, as they could do upon the Mill'd-Lead; and therefore ordered them to demand that only for the future, leaving their old Plumbers their Lead and Solder totally aside.

From the Second Axiome, and those two Tryals above mentioned, it plainly appears that the Plumbers (let them, or their Friends pretend what they will) cannot cast within ⅓ equal to the Size given th [...]o the whole Sheet: Wherefore (it having been proved above, that Mill'd-Lead is for that Reason at least ⅓ better, and will in use go ⅓ further) whatsoever the Price of Mill'd-Lead be less than ⅓ more than Cast-Lead, it must be granted that Mill'd-Lead is so much the cheaper.

Now the Price of Mill'd-Lead, Mill'd Lead Cheaper. at the Rates above supposed, being but about ⅙ more, the same is above 20 per cent cheaper, as well as better than Cast-Lead, which was to be demonstrated.

• Cast-Lead 3 hundred at 13 s. 6 d. comes to 405 s.—405.85::100. 209.
• Mill'd-Lead 2 hundred at 16 comes to—32/85—32.85::100. 265.

But if some are unwilling to grant that Mill'd-Lead is better, and will go farther than Cast-Lead, in so great a Degree as ⅓, here's Latitude enough, let them al­low half as much, and take ⅙ or any Degree under ⅛ ( the Plumbers present usual Price, being 14 s. a hundred;) within which Limit, or Proportion of Ine­quality, sure they will be satisfied that Mill'd-Lead is enough better and cheaper (besides the benefit of a more beautiful and lighter Covering) to recommend it to their Ʋse, it being one considerable advantage also, that they are sure they shall have the Mill'd-Lead smooth and sound, and of what thickness they demand; whereas the Plumber can furnish them but by guess, and that liable to concealed Blow-holes, and Sand-holes, as the Plumbers call them, which cannot be disco­vered, but where they happen, must also hasten the decay; and if they cast it so, as to bring the Charge less, or equal to the Price of the Mill'd-Lead, the Customer (if he carefully examines it) will find it to be so much thinner than the Mill'd-Lead in some places, as well as thicker in others, as to render that Covering at least 20 per cent worse; as is above demonstrated.

As to the Plumbers Pretence, That their Covering being heavier, it will yield more Money again when both come to be stript: It is not worth the answering, when it shall be considered, that Mr. Hale offers in his Advertisement (Published by it self, and Printed also in the Book above mentioned p. 93.) to Keep any Mill'd-Lead Covering, of 100 l. value, that he lays but of 7 pound to the Foot in good repair, for 41 Years (to name a Term certain and sufficient, tho it must probably last much longer) for 5 s. a Year: And that the different value of the Old Lead, after 41 Years, (if the Cast Lead should be supposed to lie so long) to be paid in ready Money is not worth speaking of, if no regard were had to the dammage a House may sustain by the leaking of a Cast-Lead Covering, and charge of patching it with Solder in the mean time.

The Book above mentioned may be had at the Booksellers following; viz. At Mr. Hensmans Shop in Westminster-Hall, Mr. Heyrick at Grays-Inn Gate, Mr. Collin's Shop by the Middle-Temple-Gate, The Harp in St. Paul's-Church Yard, The Legg and Star overagainst the Royal Ex­change, And at Mr. Mount's Shop near the Postern-Gate on Tower-Hill, And the Mill'd-Lead it self of any thickness, from a pound in a Foot, to 20 or more, for lyning of Casks or Boxes, Brewers Backs, Sisterns, Gutters, Pipes, Crowning of Vaults to prevent Leaking, and for Cover­ing of Signs, to paint on, as the Mill'd-Lead-Sign is, or any purpose whatsoever, where Sheet-Lead may be used as well as Covering Houses, and many other things that Cast-Lead cannot be applyed to. This Lead is of the usual Breadth of 3½ Foot, and may be had above twice as long as any Plumber pretends to cast, if need require, to save drips, and comply with the Length of Covering. The present Rates being for 6 l. per Foot, and all thicker at 16 s. a hundred; and for each pound in a Foot square thinner 12 d. a hundred more, at the Mill, or Wa­ter carriage paid to any place upon the River about London, if the Quantity be considerable but for small quantities under a Tun the Custo­mer pays, Boat Hire, or in lieu of Carriage 6 d. a hundred more at the Shop, and for odd Pounds under a quarter 2 d. and 2 d. half-penny the thinner sort, and Solder also at 6 d. a pound, which the Plumbers by Combination have heitherto kept up at 9 d.

At the Lead-Mill at Debtford, or at the Mill'd-Lead Sign in Aurange-street by Red-Lyon-Square, where Mr. Hale now lives, who can furnish the Customers with able Plumbers to work his Lead as there is occasion.

This Printed Paper may be had there also, and his printed Advertisement above mentioned, or at any of the Book­sellers Shops above named, gratis.