Trigonometrical Survey . 427 
served to be altered, and the thermometers nearly the same; 
at which instant, they were again read off, and the alteration 
of coincidence measured by the micrometer. 
August 5th, cloudy. 
Thermometers. 
Tvjean : 
Micr. 
Divisi 5 . 1 
Total con tr. 
Inches. 
Contr. 
on 3°, 
Inches. 
1 
2 
3 , 
4 
5 
7575 
62,5 
75,5 
62,75 
76 
63 
76,25 
63 
76 
63 
7 5’9 
62,85 
2 5f 
,096642 
,0074 
Here the contraction of the chain is 25I divisions of the mi- 
crometer = 25! x inches =,096642 inches, and the cor- 
responding variation of the thermometers, taking the diffe- 
rence of the means, is 13°, 05 ; consequently the contraction 
on i° = = ,0074 inches, 
Aug. 6th, cloudy. 
89>5 
69.5 
8975 90 
69,5 69,25 
9° 9°>5 
69 69,5 
89 ’.95 
69,35 
,148.077 
,0071 9 
Aug. 7. Coffers covered with the linen cloth. 
102,5 
102,75 
102 
102 
102,35 
29’5 
8 
86 
87 
88 
88 
87,2 
89,75 
.93 
92 
92 
9 1 » 1 5 
16,25 
9,33 
95 
102 
99,75 
101 
99,15 
92 
96 
95 
95,75 
94,35, 
,113462 
,030769 
,062500 
,035885 
,00749 
,00779 
,00781 
,00748 
