FLAttSTONE ROOF. g5 



effect this purpose, grooves were cut into the upper surface joints covered 



alon^ each side of every flag three quarters of an inch deep 



at one inch from the edge, see tig. 2 and 3, where a section or 



profileis given. To cover these lateral joints caps of lead were 



laid from the ridge to the eaves, a cap for each flag, or 



rather for every pair of flags. These caps, which had the 



appearance of a bead, were fastened over the rabbets or 



grooves of the flags by copper nails, c, driven through the 



caps into the juncture between the flags. These nails were 



made fast by slips of sheetlead d d iig. 3, put between the 



stones. A representation of the full size of the grooves in 



the stones of the lead cap and mushroom nailsis given, fig. 3. 



Where holes were made through the lead caps, the water 

 might find a passage; but this was prevented by preparing 

 the holes in the lead in such a manner, as to stop the water 

 above the hole, and to turn it aside from the direction which 

 might be hurtful. The caps before they were laid in their 

 proper places were turned upside down, and where nails 

 were to pass, a burr or button, b, 6, was punched in the 

 lead half an inch deep, and by a proper tool passing through ' 



the punch, a hole was made in the centre of the button. 

 The cap, when put into its place, covered the ridges of the 

 flags between the grooves, so that no water could find an 

 entrance between the joints of the flags ; nor could any 

 water rise above the tops of these buttons, because the Th;$ effectual, 

 descent of the roof would carry it off". Besides, the button 

 or burr was covered by a mushroom-headed nail , the rim of 

 which entered a little into the lead round the burr and pre- 

 vented small particles of snow from gaining admittance. 



The holes in these caps might have been closed by solder; 

 but whenever any work that is of difficult access is to SimpHcitv ad- 

 be performed, it is always advantageous to have it executed ^^"^^K^°"=*' 

 by some one workman, in a manner that requires no diffi- 

 cult art or complicated apparatus. And I find that not one 

 drop of water has penetrated through these joints during 

 the two winters that have passed since they were covered 

 according to this plan. 



At the commencement of the business many difficulties Difficulttea 

 with respect to the scaffolding were started. Very long thI^s<SoldiM 

 ladders were requisite. Cripples hung on iroji stauncheons 

 G2 in 



