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and are loth that our own country fhould unite two follies in a publick work.

The architrave of Perault, which has been pompously produced, bears nothing but its entablature; and is fo far from owing its fupport to the artful fection of the stone, that it is held together by cramps of iron; to which I am afraid Mr. M-muft have recourse, if he perfifts in his ellipfis, or, to use the words of his vindicator, forms his arch of four segments of circles drawn from four different centres.

That Mr. M— obtained the prize of the archi~ tecture at Rome, a few months ago, is willingly confeffed; nor do his opponents doubt that he obtained it by deferving it. May he continue to obtain whatever he deserves; but let it not be prefumed that a prize granted at Rome, implies an irresistible degree of skill. The competition is only between boys, and the prize given to excite laudable industry, not to reward confummate excellence. Nor will the fuffage of the Romans much advance any name among those who know, what no man of science will deny, that architecture has for fome time degenerated at Rome to the lowest state, and that the Pantheon is now deformed by petty decorations.

I am, SIR,

Yours, &c.

SIR,

LETTER

III.

Dec. 15, 1759.

IT is the common fate of erroneous pofitions, that they are betrayed by defence, and obfcured by explanation; that their authors deviate from the main queftion into incidental difquifitions, and raise a mist where they should let in light.

Of all these concomitants of errors, the Letter of Dec. 10, in favour of elliptical arches, has afforded examples. A great part of it is spent upon digresfions. The writer allows, that the first excellence of a bridge is undoubtedly ftrength; but this conceffion affords him an opportunity of telling us, that strength, or provifion against decay, has its limits; and of mentioning the Monument and Cupola, without any advance towards evidence or argument.

The first excellence of a bridge is now allowed to be Strength; and it has been afferted, that a femi-ellipfis has lefs ftrength than a femicircle. To this he first anfwers, that granting this pofition for a moment, the femi-ellipfis may yet have strength sufficient for the purposes of commerce. This grant, which was made but for a moment, needed not to have been made at all; for before he concludes his Letter, he undertakes to prove, that the elliptical arch must in all respects be fuperior in ftrength to the femicircle. For this daring affertion he made way by the intermediate paragraphs; in which he obferves, that the convexity of a femi-ellipfis may be increafed at will to any degree that ftrength may require; which is, that an elliptical arch may be made Jefs elliptical, to be made lefs weak; or that an arch,

which

which by its elliptical form is fuperior in ftrength to the femicircle, may become almoft as ftrong as a femicircle, by being made almost femicircular.

That the longer diameter of an ellipfis may be fhortened, till it fhall differ little from a circle, is indifputably true; but why fhould the writer forget the femicircle differs as little from fuch an ellipfis? It feems that the difference, whether fmall or great, is to the advantage of the femicircle; for he does not promife that the elliptical arch, with all the convexity that his imagination can confer, will ftand without cramps of iron, and melted lead, and large ftones, and a very thick arch; affiflances which the femicircle does not require, and which can be yet lefs required by a femiellipfis, which is in all refpects fuperior in ftrength.

Of a man who loves oppofition fo well, as to be thus at variance with himfelf, little doubt can be made. of his contrariety to others; nor do I think myself entitled to complain of difregard from one, with whom the performances of antiquity have fo little weight: vet in defiance of all this contemptuous fuperiority, I must again venture to declare, that a trait line will hear no weight; being convinced, that not even the fcience of Vajari can make that form ftrong which the Jaws of nature have condemned to weaknefs. By the pofition, that a frait line will bear nothing, is meant, that it receives no firength from firaitnefs; for that many bodies, laid in ftrait lines, will fupport weight by the cohesion of their parts, every one has found, who has feen difhes on a fhelf, or a thief upon the gallows. It is not denied, that ftones may be fo cruthed together by enormous preffure on each fide, that a heavy mafs

may

may fafely be laid upon them; but the strength must, be derived merely from the lateral refiftance; and the line fo loaded will be itfelf part of the load.

The femi-elliptical arch has one recommendation yet unexamined; we are told that it is difficult of execution. Why difficulty fhould be chofen for its own fake, I am not able to difcover; but it must not be forgotten, that as the convexity is increased, the difficulty is leffened; and I know not well whether this writer, who appears equally ambitious of difficulty and studious of ftrength, will wish to increase the convexity for the gain of strength, or to leffen it for the love of difficulty.

The friend of Mr. M, however he may be mistaken in some of his opinions, does not want the appearance of reafon, when he prefers facts to theories; and that I may not difmifs the queftion without fome appeal to facts, I will borrow an example, suggested by a great artist, and recommended to thofe who may still doubt which of the two arches is the stronger, to press an egg first on the ends, and then

upon the fides.

I am, SIR,

Yours, &c.

SOME

THOUGHTS

ON

AGRICULTURE,

Both ANCIENT and MODERN:

With an Account of the Honour due to an ENGLISH FARMER*.

A

GRICULTURE, in the primeval ages, was the common parent of traffick; for the opulence of mankind then confifted in cattle, and the product of tillage; which are now very effential for the promotion of trade in general, but more particularly fo to fuch nations as are most abundant in cattle, corn, and fruits. The labour of the Farmer gives employment to the manufacturer, and yields a fupport for the other parts of a community: it is now the fpring which fets the whole grand machine of commerce in motion; and the fail could not be spread without the affiftance of the plough. But, though the Farmers are of fuch utility in a state, we find them in general too much difregarded among the politer kind of people in the present age; while we cannot help obferving the honour that antiquity has always paid to the profeffion of the husbandman: which naturally leads us into fome reflections upon that occafion.

Though mines of gold and filver fhould be exhaufted, and the fpecies made of them loft; though

• From the Vifiter, for February 1756, p. 59.

diamonds

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