33 8
THE LIFE OF
quibus tamen, nulla alia prorsus fuppetente materiel, pro contignatione con fid enJanecefjario erit utendum : Sfuid obfecro miser ille ArchiteBus Jibi confilii capict ?Rationem Me deferiptam perfequetur, et opus fuum qnam solidifjimum reddet , al-tcro niminim tignorum capite parieti infixo, reliquoque abfque ulla fultura fits-penso remanente , quemadmodutn ex JubjcBd perspici poteji Figurd.
Sebajliani Scr Hi Diagramma Contignationis planes Geometric œ.
A Model of a crermet rir.nl Vint- floor contrived hv Dr. C Y IVeillie wn<; crivert
0 f to the Royal Society by Bishop IVUkins ; the following Account ot which, by' the Author, is an Abstract of that he hath published in his Book De Motu ,Cap. vi. Prop. 10. Fig. 243.
ettetery, c&g* jt * T O tj
z6i. I did first, faith the Doctor, contrive and delineate it, in the Year 1644, at
Queen’s-college in Cambridge. When afterwards I was made Professor of Geo-
metry at Oxford , about the Year 1650, I caused it to be framed of smallPieces of Timber, prepared by a Joiner, and put together by myself.
This I shewed soon after to divers in Oxford, and particularly to Dr. Wtl-kins, then Warden of Wadham College. After the King’s Rejlauration, I causedanother to be made; and in the Year 1660, presented it to his Majesty, whowas well pleased with it, and caused it to be reposited in his Closet.
On the Model first-mentioned, I read two publick he Bur es at Oxford ; theone, in the Year 1652, as to the Construction of it; the other, in the Year1653, as to the Computation of what Weight every Joint of it sustains;whereby it might be the better judged how far it may be safely practised.The greatest Weight charged on any one Joint, doth not amount to ten timesthe Weight of one Beam ; and the greatest Weight borne by one Beam, notto seventeen times its own Weight: And even this, not laid all on the samePart, but distributed to several Parts of it.
A third LcBure , much to the same purpose, I read May 1669, in the samePlace, before the Grand Duke of ‘Tuscany.
The Contrivance is obvious to the Eye. The Outsides represent the Wallsof the Building, on which this Flat-floor or Roof is to be laid. The Beamsnext adjoining to the Sides, have one End lodged on those Walls; the otherEnd sustained by another Beam, lying cross; both Ends of which, are inlike manner sustained by other Cross-beams; and, those again by others;till they reach the other Walls. So that no one of them can fall, unlessthe Walls fail, or the Beams break: All mutually sustaining each other,without any Pillar or Prop to support them, besides the outer Walls.
The Models I caused to be made, and that of the.Royal Society in Imi-tation thereof, are in Breadth about four times as much as the Length of
the longest Beam ; but may be continued, at Pleasure, to farther Breadth, 'as shall be thought fit; with this Caution, that the farther the Work is con-tinued, the greater Weight will be charged on every Joint; especially near theMiddle. And tho’ in this Model, no one Beam is charged with so much asseventeen times its own Weight; yet if the Work be continued to a greaterBreadth, the proportional Weight will be thereby increased. And thereforemust be limited, according to the Strength of Timber, able to bear more orfewer times its own Weight.
I do not know, that yet it hath been reduced to Practice, in more thanfour Pieces in this Form. Such is one of the Floors in the Tower of thepublick Schools at Oxford: The Breadth whereof, to the Length of theBeams, is as three to two. But may doubtless be continued much further;especially in such a Roof, as is not to bear much more than its ownWeight.
Thus,
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