138 Expansion and Contraction of Building Stone. 
sixty degrees Fahr. But to abridge the calculation, the difference 
in length between the stone and measuring rod, as shown by the 
wedge W, was subtracted from the length of the rod before making 
the reduction for the temperature of the latter. The length of the 
copper part, and that of the wooden part, were calculated separate- . 
ly on account of their different expansibilities. The result of this 
calculation is the following table. 
MARBLE. GRANITE. SANDSTONE. 
No. of | Degrees| Length in | Degrees| Length in | Degrees} Length in 
Experi. | Fahr. Inches. Fahr. Inches. Fahr. “Inches. 
1 6° | 93.4155 6° | 94.025] 6° | 94.0180 
2 7 93.4277 8 | 94.0330 8 | 94.0153 
3 9 93.4201 9 94.0260 9 | 94.0052 
4 10 93.4207 10 94.0265 10 94.0088 
5) 11 93.4131 11 94.0230 At 94.0124 
6 12 93.4186 12 94.0282 13 94.0211 
7 14 93.4174 14 94.0271 14 94.0206. 
8 14 93.4294 14 94.0347 14 94.0220 
9 14 | 93.4308 14 | 94.0361 | 15 94.0235 
10 16 93.4302,} 16 94.0285 15 94.0238 
11 16 93.4291 16 94.0345 17 94.0214 
12 17 93.4305 17 94.0358 18 94.0181 
13 19 93.4327 19 94.0416 | 20 94.0239 
14 20 93.4310 | 20 94.0364 | 22 94.0258 
15 21 93.4316 | 21 94.0440 | 22 *| 94.0263 
16 ol 93.4265 32 94.0324 32 94.0371 
17 32 93.4352 | 32 94.0406 34 | 94.0466 
18 34 93.4422 36 94.0330 38 94.0554 
19 36 93.4360 | 36 94.0150 39 94.0436 
20 36 93.4357 | 37 94.0483 39 94.0592 
24 Were oie) 93.4436 41 94.0344 43 94.0486 
22 82 | 93.4323 52 94.0348 53 | 94.0560 
23 58 93.4450 62 94.0541 64 | 94.0718 
24 83 93.4655 86 94.0720 3 94.0879 
25 86 93.4649 88 94.0737 93 | 94.0829 
26 90 | 93.4709 88 94.0688 95 94.0897 
27 59 93.4677 89 94.0731 99 94.0941 
28 : Sa as 90 94.0693 | 100 94.0906 
29 : Bh a 91 94.0693 | 101 94.0944 
30 5 otis 94 94.0628 | 104 94.0841 
3l ; feb 102 94.0721 | 109 | 94.0792 
It is probable that many of the discrepancies here noticed were 
owing to the hygrometric state of the stone; and perhaps, in part, 
to imperfections in the measuring apparatus; but as the hygrome- 
