274 I'HILOSOl'HICAL TKANSACTIONS. [aNNO J79'i. 



They were afterwards brought back again to 60" of temperature ; when the spirit 

 in the long instrument stood 3 above O, as before, but in the short instrument 

 5.5 below 0. I then heated them up to lOO", and it stood in the long instru- 

 ment at 234, and in the short instrument at 226, above O. They were again 

 brought to the temperature of 60°; when it was found to stand in the long in- 

 strument at O, and in the short instrument at 8 below O. 



From the above experiments it appears, that the contraction by the long in- 

 strument, in cooling down from 6o° to 30°, is 161.5 -|- 3 = l64.5, and the ex- 

 pansion in heating up again to 60*^, the same. In heating up from 60° to 100°, 

 234 — 3 = 231 ; but the contraction in cooling down again from 100° to 6o°, 

 234; the mean is 232.5, and the total expansion from 30'' to 100° = 397, dif- 

 fering from the experiments by weight 0.55 of a division, in defect: but if no 

 mean be taken, the deficiency will appear greater. The difference between heat- 

 ing up from 60° to 100°, and cooling down again from 100° to 6o°, is 3 divisions, 

 still more considerable in this than in the last experiment. 



The contraction by the short instrument from 6o° to 30° is 167.5 — 5 ^ 

 162.5, and the expansion from 30° to 6o° again 167.5 — 5.5 = l02; the mean 

 is 162.25. On heating up from 6o° to 100°, 226 -f 5.5 = 231.5; but the con- 

 traction, in cooling down again from 100° to 6o° was 226 -j- 8 = 234; the mean 

 is 232.75, and the total expansion from 30° to 100° = 395 ; differing from the 

 experiments by weight 2.55 divisions, in defect. The difference between heat- 

 ing up from 60° to 100°, and cooling down again from 100° to 6o°, is 2.5 divi- 

 sions. After the above experiments had been made, the spirit was let out, and, 

 on a subsequent day, the 2 instruments were charged again with some of the 

 same spirit, previous to the following experiments. 



After bringing the spirit to the temperature of 6o°, I found it to stand in the 

 long instrument 6 above O, and in the short instrument 2 below O. I cooled the 

 spirit down to 30°, when it stood in the long instrument 158.5, and in the short 

 instrument ]66, below O. I brought it again to the temperature of 60°, and it 

 returned to the same point it set off from, in both instruments. Tlie spirit was 

 then heated to 100°; when it rose in the long instrument to 235, and in the 

 short instrument to 230, above O. I cooled it again to the temperature of 60°, 

 when it was found to stand in the long instrument 1 below O, and in the short 

 instrument 5 below 0. 



It appears, from the above experiments, that the contraction by the long in- 

 strument in cooling down from 6o° to 30° is 158.5 + 6 = 164.5, and the ex- 

 pansion in heating up from 30° to 6o°, the same. On heating up to 100°, 235 

 — 6 = 22g, but the contraction in cooling down from lOO" to 6o° again, 235 

 -f I = 236; the mean is 232.5, and the total expansion from 3t)° to 100° = 

 397 .0; diflering from the experiments by weight 0.55 of a division, ia defect; 



