E D D

329

E D D

brTTT~

foclq ami ' were about 41 inches broad at the surface of tirelr U° th e at t * le k° ,tom > and this being first put downat) , “°‘ e > the space left for a key would be 3 inches at^ inches at bottom, which would admit it to be®*ed m* 1 80 as to render the whole firm, and the main branch11 e a dove-tail or lewis.

te sp ec tj 6 "°les being each finished, and fitted with their? Ua Htit v 6 branches, and cleared of water, a considerable^icli me lted tallow was poured into each hole: thePit <] 0 ^ ari ^ key being then heated to about a blue heat, andn 4ce UnfiiV 1 * 0 t ' le tallow, and the key firmly driven, all thel( i ovf., 1 ^ ky the iron, would become full of tallow, andI^i'ainff Wade t0 run over : when this was done, allN in k°t, a quantity of coarse pewter, being made red-t>0 dy ) a ale, and run into the chinks, as being the heaviestd c k'ive out the superfluous melted tallow : and so

S? '“ d ■ ■

which

this operation succeeded, that in those, t], "‘ucn were cut out in 1756, and had remainedo n i y ole cavit y kad continued so thoroughly full, thatle pewter, but even, in general, the tallow, remainedy fresh : and when the pewter was melted from thescale appeared upon the iron, as if it had comesmith’s forge, without the least rust upon it.

iron branches, which are shown, as I found

FTf vT

Al > the

*rn, W „1«11 UIC DllUVVll, U5 X 1UU..U

onL. n 1 “ 0 ne(1 in 1 e T > havin g been fixed in the manner aboye-bulk ’^ey next proceeded to lay a course of squared’ len gthwise upon the lowest step, and of a size totyg 0 t '.“ e level of the step above. Then a set of shortt | Pcorn* 6 * a ' d crosswise of the former, and upon the nextt'^edly, so as to make good up to the surface ofThe third stratum was therefore again laidO an d the fourth crosswise, &e., till a basement of^8h(. g j Was raised, two complete courses higher than the'l/' to tl rt ’' ie ro<: k 5 the whole being fitted together,itn e * e r ° c k, as close as possible, and the balks, in allCf 6 lC« eCti ° nS "'ith each other, trenailed together. Theyi n _ ktted to the iron branches where they happened

with

a «y 0 f ° r branches do not seem to have been placedph^Sth ail °! n fk e te regularity or order, but rather where the<lis 8 fur f mness of the rock pointed out the properest. e d s 0 1Xln ° them; they were, however, to appearanceaS to ferin a double circle, one about a foot withinV ' v ‘ t lij ri ei . ence °f the basement, and the other about three*it)e (; s fl le former ; besides which, there were two large>r ‘r^ °f a l a ^ ed near the centre, for taking hold of the two“ by u P r ight piece of timber, which was called the

1 b,

lltlo

two branches it was strongly fixed down

Which

r^ t Set f Perpendicular, it served as a centre for guiding% h r . l ke succeeding work.

it, o s > So ttle ' l J l( ^bes were perforated, in their respective upper

n«: "'.kb three, and some with four holes ; so that,

‘Im:'P an-_.... .x,,_’

(collectively called a branch) there would be atbr a Ve . n holes ; and as there were at least thirty-six. * es > there would be 252 holes, which wereJ‘; ei ghths of an inch in diameter ; and, conse-

capable of receiving as many large-bearded

f, 0 liif b0lt ' S ’ which being driven through the branches'\g 'Vn. timber, would undoubtedly hold the whole massK t i Sf ' c tl Qris * an d the great multiplicity of trenails in the'' / Would confine all the strata closely and coin*

\ lca C er --

\ a " r can // ,nU liei ' e to remark, that though the instrumentLSlo iculn - C ^ etois > Is of an old date, yet, so far as appears,in'f a PPhcation of that idea, which Mr. Rudyerd\ 0 f 1Xl »g his iron branches firmly to the rock, was^ ta nl T tlle first time in tllis work : for thoughe J r mentions his having made twelve holes, and4 p

fixed twelve great irons in the rock, in his first year’s work,yet he gives no intimation of any particular mode of fixingthem, but the common way with lead; and the stump of oneof the great irons of Mr. Winstanley’s, that was cut out inthe course of the work of the summer of 1756, was fixed inthat manner; but we remarked, that the low end of this baror stanchion, was a little club-ended, and that the hole wassomewhat under-cut; so that, when the lead was poured in,the whole together would make a sort of dovetail engraft-ment: however, when these irons, by great agitations, becameloose, and the lead yielded in a certain degree, they wouldbe liable to be drawn out; as the orifice by which theyentered must have been large enough to receive the iron club.Mr. Rudyerd’s method, therefore, of keying and securing,must be considered as a material accession to the practicalpart of engineery ; as it furnishes a secure method of fixingring-bolts and eye-bolts, stanchions, &c., not only into rocksof any known hardness ; but into piers, moles, &c., that havealready been constructed, for the safe mooring of ships ; orfixing additional works, whether of stone or wood.

“ In this way, by building stratum super stratum, of solidsquared oak timber, which was of the best quality, Mr. Rud-yerd was enabled to make a solid basement of what heighthe thought proper: but in addition to the above methods, hejudiciously laid hold of the great principle of engiheery, thatweight is the most naturally and effectually resisted by weight.He considered, that all his joints being pervious to water,and that though a great part of the ground-joint of the wholemass was in contact with the rock, yet many parts of itcould not be accurately so ; and therefore, that whateverparts of the ground-joint were not in perfect contact, so asto exclude the water therefrom, though the separation wasonly by the thickness of a piece of post-paper, yet if capableof receiving water in a fluid state, the action of a wave uponit edgewise, would, upon the principles of hydrostatics,produce an equal effect towards lifting it upwards, as if itucted immediately upon so much area of the bottom as wasnot in close contact.

“ The more effectually therefore to counteract everytendency of the seas to move the building in any direction,he determined to interpose strata of Cornish moor-stonebetween those of wood ; and accordingly having raised hisfoundation solid, two courses above the top of the rock, hethen put on five courses, of one foot thick each, of the moor-stone. These courses were as well jointed as the workmenof the country, could do it, to introduce as much weight aspossible into the space to contain them : they were, however,laid without any cement; but it appears that iron crampswere used, to retain the stones of each course together, andalso upright ones to confine down the outside stones.

“When five feet of moor-stone were laid on, which,according to the dimensions, would weigh 120 tons; he theninterposed a couple of courses of solid timber, as before ; theuse of which was plainly for the more effectual and readyfastening of the outside uprights to the solid, by means ofjag-bolts, or screw-bolts ; and that these bolts might themore effectually hold in the wood, in every part of the circle(which could not be the case with timbers lying parallel toeach other, because in two points of the circle, oppositeto each other, the timbers would present their ends towardsthe bolt) he encompassed those two courses with circular,or what are technically called compass timbers , properlyscarfed together, and breaking joint one course upon theother. We must not, however, suppose, that these courseswere composed wholly of circular timbers to the centre, butthat the circles of compass timbers on the outside werefilled up with parallel pieces within ; and that the compass