LIGHT-HOUSES.

359

Mr. John Smeaton was recommended by llie President ofthe Royal Society , who appears to have been well qualifiedfor the undertaking;. He accordingly furnished a plan for,and superintended the building which now stands. Mr.Smeaton ’s conception was quite different to that of the lastprojector: he conceived that nothing could withstand theaction of the wind and water so well, and, at the same time,prevent all accidents like the last, as could a building whosegravity should secure its most sure protection. He accord-ingly constructed his of the most massy stones, all dove-tailed into each other, formed of Cornish moor and Port-land stone; all the joints breach each other, as the masonsterm it, or on each joint occurs the central stone of the nextcourse. There are fourteen courses of these stones first laidin this manner, of a great thickness each course. On the12th June, 1757, the first stone was laid in its place, eachstone being pierced when it was laid, a strong trenail, oroak pin, was driven through to pin it fast to its place : thedovetails not fitting so close to each other, because it wasnecessary to leave some space for the cement, this pin wascalculated to secure the stone till this could be applied andhad fixed; the cement used was composed of Watchet limeand puzzolana, or Dutch terras, being made at the momentby mixing up in a pail with water; this mixture was pouredupon the work and ran into every cavity and crevice; this,however, was not sometimes exempt from the injury of thesea; wdienever it was injured, the defect was supplied byhaving some oakum, cut fine, and mixed with this cement,introduced into the joints; then they were secured with acoat of plaister of Paris , pro tempore, and this was neverknown to fail, if the work stood for one tide. In this man-ner the platform was erected, all of the most solid materialsand substantial workmanship. On the 30th of September,1758, the work having been continued from the 11th of thepreceding May, had arrived at the store-room floor,—herean iron chain was let into the stone, as follows: the recessbeing made, and the chain well oiled before insertion, thegroove which received it was divided into four separatedams by clay; two kettles were used, to hold a sufficiencyof fused lead, llcwt.: whilst the lead was in a state offusion, two men with ladles filled one quarter of the groove;as soon as it was set, they removed one of the clay dams,and then filled the next quarter, pouring the " _ ’ ’ lead onthe middle of the first quarter, till it melted together intothe second; the dam at the opposite end was now filled, andthen the fourth, by this means the lead was associated intoone solid mass. The centring for the floor was next set up,