THE LIFE OF

Honour of it ; for, neither will the Flower-de-luce of the Ttcnck, nor the Palmsof Villalpandus, in his imaginary Scheme of the Temple of Solomon, come upto the Grace of the old Form of the Corinthian Capital.

It seems very Unaccountable, that the Generality of our late Architects dwellso much upon this ornamental, and so slightly pass over the geometrical, whichis the most esiential Part of Architecture. For Instance, can an Arch stand with-out Butment sufficient ? If the Butment be more than enough, ’tis an idle Ex-pence of Materials; if too little, it will fall; and so for any Vaulting : And yetno Author hath given a true and universal Rule for this; nor hath consideredall the various Forms of Arches.

The Rule given by the Authors for the Butment of Arches, is this: [SeeFigure I. ] Let ABC be the Arch, of which B is a third Part; extendthe Line B C, and make CD equal to C B, and draw the Perpendicular CDF,this determines the Butment G F, (as they fay) but wherefore ? for add to theBottom, as K L, the Arch then must certainly press more upon the higherPart than the lower; or if some additional Weight be added above the Arch,that must still press more than before this was added. So this Rule (if it werebuilt upon any sure geometrical Theorem, as it is not) is neither true nor uni-versal ; and what is true will be strewn to be only determinabie by the Doctrineof finding the Centers of Gravity in the Parts of the proposed Design. In de-monstrating this, I will not trouble the Reader with nice geometrical Specula-tions, or Calculations, but by easy Inductions; supposing he hath read Archilmedes, or the modern Geometricians, who have purposely treated of Centers ofGravity ; or at least, that he will give Credit to those who have established allthe Principles of this Science by Demonstration unquestionable; so it will not benecessary to dive into the Rudiments.

Fig. II. Let a Stone be cut in this Form, F B a Parallelogram, C D a Semicircle added,

A B a Perpendicular, M the Center of Gravity of F B, and N of A C D, nowif N be equiponderant to M on each Side the Perpendicular A B, it is certainthe whole Stone will stand immoveable upon the Basis at B, although it be buthalf an Arch ; add the like Stone on the opposite Side, till the Horns meet in anentire Arch, so the Whole will stand as well as the Halves. If any thing beadded without M, that alters nothing, only ’tis an useless Expence; but if anything be added above N, that alters the Center of Gravity, which therefore mustbe provided for, by adding more Weight to M; and the fame may be strewn inall kinds of Vaulting. So it appears that the Design, where there are Arcades,must be regulated by the Art of Staticks, or Invention of the Centers of Gravity,and the duly poising all Parts to equiponderate ; without which, a fine Designwill fail and prove abortive. Hence I conclude, that all Designs must, in thefirst place, be brought to this Test, or rejected. I have examined some celebratedWorks, as the Pantheon, and judge there is more Butment than necessary, thoughit is flat and low; but I suppose the Architect provided it should stand againstEarthquakes, as indeed it hath, and will. The great Fabrick of St. Peter’s, ifit had been followed as Bramante had designed it, would have been as durable;but the Butment of the Cupola was not placed with Judgment: however, sinceit was hooped with Iron, it is safe at present, and, without an Earthquake, forAges to con\e. Iron, at all Adventures, is a good Caution; but the Architectshould so poise his Work, as if it were not necessary.

The Freq-mafons were not very solicitous about this, because they used But-trefles on the Outside of the Wall, which they extended as far as they guessedwould be sufficient ; and they had yet a farther Help, by loading the Buttresswith a Pinnacle, to the Height of which they were not confined. The Ro-mans never used Buttresses without, hut rather within, though they cut off aPart of the Arch, but not of the Vaulting that depended on the Arch, as it'5 appears