Chap. VIII.
369
The main pieces of each branch were, at the surface of the rock, 4J inches in breadth,and at the bottom 6£ inches; when introduced into the hole, there was space left toadmit a key, which, at thebottom, was 2 inches, andat the top 3 inches, which,when driven, fixed thewhole in the manner of adovetail or lewis.
The holes being fittedwith the branches, a quan-tity of melted tallow waspoured into each ; thebranch and key beingheated to a blue heat wasput into the tallow, andthe key firmly driven, sothat the space which theiron did not occupy wasfilled with tallow; afterthis was done, and whilstthe iron was warm, aquantity of pewter, madered-hot, was poured infrom a ladle, which beingheavier than the tallowdrove it out. Many yearsafterwards, when theseirons were cut out, theiron, pewter, and tallowwere found unaffected bythe action of the sea-water,which apparently hadnever penetrated into theholes which contained .them.
After these irons werefixed, a layer of squaredoak timber was placedlengthways upon the low-est step of the rock, and ofa depth to reach to thelevel of the next above.
Over these were laid cross-wise another layer oftimber; and above this,others, taking care to crosseach alternate course, untila mass of timber was piledup two complete courseshigher than the highestpart of the rock, and thesewere all trenailed together.
In the middle of this seriesof timber platforms stoodan upright mast, whichwas firmly secured to therock by two stout irons ;this mast served as a centrefor guiding all the restof the superstructure, asthere were altogether 36of these branch irons, ineach of which was bored ahole, seven-eighths of aninch in diameter, andthrough these 252 holes Fi *- 371 - winstanlby's l.ghthousb.
passed as many bearded spikes, or jag bolts, which held the several layers of timber together.
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