on the strength of materials. 131 
In the following experiments on stones, the pressure was 
communicated through a kind of pyramid, the base of which 
rested on the hide leather, and that, on the stone. The lever 
pressed upon the apex of the pyramid. Cubes of one and a 
half inch. 
specific gravity, lbs. avoirdu. 
105 Chalk - - - - 1127 
106 Brick of a pale red colour - 2.085 1265 
107 Roe stone, Gloucestershire - - 1449 
108 Red brick, mean of two trials - 2.168 1817 
109 Yellow face baked Hammersmith paviors 3 times 2254, 
110 
Burnt do. mean of two trials 
3243 
111 
Stourbridge or fire brick - 
- 
3864 
112 
Derby grit, a red friable sand stone 
2.316 
7070 
113 
Ditto, from another quarry 
00 
c* 
ci 
977 6 
114 
Killaly white freestone, not stratified 
2.423 
10264 
115 
Portland 
2.428 
10284 
ll6 
Craig Leith, white freestone 
2.452 
12346 
June 5th, 6th, and h ]th, 1817. 
117 
Yorkshire paving with the strata 
2.507 
12856 
118 
Ditto, do. against the strata, 
2.507 
12856 
119 
White statuary marble not veined 
2.760 
33632 
120 
Bramley Fall sand stone, near Leeds, 
with strata 
2.506 
13632 
121 
Ditto, against the strata 
2.506 
13632 
122 
Cornish granite 
2.662 
1430 2 
123 
Dundee sand stone or Brescia, two 
kinds - 
2.530 
14918 
124 A two inch cube of Portland 
2.423 
14918 
