268 WW METHOD OF SLATING, 



New mode of to them by dove-tailed joints as aforesaid, constitute, for 

 scribed. these intervenient rafters, abutments as immovable as those 



of the beaftu-rafters themselves ; and which, like those, be- 

 ing firmly fastened to the purloins F F, at their centres, and 

 to the first-pieces at their upper ends; while these first-pieces 

 remain unbent in an upward direction, and the wall-plates 

 are found immovable outwards, they form, each pair of them, 

 as permanent an arch as the beam-rafters themselves ; and 

 thus aiding the latter, they altogether constitute, as afore- 

 said, a frame of such singular and uniform strength and 

 stability, as undoubtedly to be capable of sustaining at least 

 any weight that it may ever be necessary to" lay on it. 



H H H, figs. 1, 2, Deal laths, each an inch thick, and 

 two inches wide, their lower half rabbited for receiving the* 

 tipper ends of the slates, in depth equal to the thickness of 

 the latter. 



1 1, figs. 1, 2, Slates, nailed nearly at their centres to the 

 tipper parts of the laths, the nails clenched, and the slates 

 cemented on both sides to each other with putty, or any 

 other matter proper for uniting them ; and thereby effectu- 

 ally excluding rain, wind, driving snow, and all aerial hu- 

 midity. 



K K, fig. 2, Ceiling-joists inserted in the foot-beams after 

 the usual manner. 



L, fig. 2, A portable stage or scaffold for the slater to 

 work on between the rafters, for keeping at all times under 

 his thumb a new and appropriate set of simple implements, 

 (as usefully employed by rational beings in all other matters) 

 and occasionally, as the work proceeds, to be drawn back- 

 ward on the ceiling-joists. 



M, fig. 1, The slater seated between the rafters on his 

 stage, with his work before him, and immediately under his 

 eye. 



N, fig. 7, A discharging saw, that, being of proper tem- 

 per, and having a series of teeth about three inches down on 

 each side from its point, is occasionally introduced by a 

 hammer at its heel, and thus removes putty, nails, &c. from 

 a broken slate ; when a new one, supplying its place, will, 

 with a little putty under its lower edge to cement it, become 

 quite as effectual, if not as firm, as the original one. Pro- 

 bably, 



