OF THE VIBRATIONS OF AN INVARIABLE PENDULUM. 
223 
Whence it appears as the result of this experiment, that a difference of 9.54 
vibrations per diem corresponds to a difference of atmospheric pressure of 
27-459 inches of mercury at 32° ; the temperature of the air of full pressure 
being 35°.89, and that of the rarefied air 36°.5. 
The trifling leakage of the apparatus in this and the following experiment 
was attributed, and as it was afterwards proved justly, to the severity of the 
weather, which hardened the pomatum so that it did not secure the joinings of 
the glasses so well as usual. 
Exp. IV. — January 17th and 18th. Clock gaining 4 m 14 s .38. 
Observer. 
No. of 
Coincid. 
Thermometers. 
Stand- 
ard 
Barom. 
Times of 
Arc registered 
and true Arc. 
Mean 
Interval. 
Correc- 
tion for 
Arc. 
Reduc- 
tion to 
36°. 
Corrected 
Vibrations 
at 36°. 
1 
2 
3 
4 
Disapp. 
Re-app. 
Coincidence. 
f 
Captain J 
Sabine. 
L 
1 
2 
3 
19 
20 
21 
o 
O 
O 
O 
inch. 
m s 
16 24 
24 38 
32 51 
45 04 
53 21 
01 37 
m s 
16 36 
24 53 
33 06 
45 28 
53 49 
02 05 
"1 h m s 
Ml 24 44.67 
1 53 34 
Div. o 
0.785 = 0.94 
0.29 =0.35 
Is 
>496.08 
+ 0.64 
s 
-1.54 
86304.13 
32.3 
32.2 
32.4 
32.4 
29.65 
:::::: 
32.4 
32.3 
32.5 
32.4 
29.66 
32.35 
29.655; Capill. + 0.019; Redaction to 32° — 0.004; =29.670. 
86304.13 
The air was then withdrawn, and the following observations made ; the 
valves of the pump requiring repair, the gauge could not be reduced lower 
than 3 inches. 
Observers. 
Captain J 
SabineA 
Captain J 
Sabine. ] 
Mr. f 
TaYLOR.) 
1 
2 
3 
20 
21 
22 
60 
61 
62 
Thermometers. 
12 3 
31.7 
31.8 
31.6 
32.3 
32.2 
32.2 
32.5 
32*4 
32.2 
32.6 
32.4 
32.4 
31.7; + 0.75 = 32.45 
Gauge. 
inch. 
3.09 
3.48 
4.19 
Times of 
Disapp. 
Re- 
rpp. 
Coincidence. 
m 
S 
m 
s 
07 
35 
07 
48 
1 h 
m 
S 
16 
03 
16 
18 
> 3 
16 
10.17 
24 
31 
24 
46 
J 
48 
33 
48 
55 
1 
57 
01 
57 
25 
r b 
57 
12.83 
05 
29 
05 
54 
j 
28 
16 
28 
36 
i 
36 
48 
37 
08 
>n 
36 
58.33 
45 
20 
45 
42 
/ 
3.59 
Arc registered 
ancWrue Arc. 
Div. o 
0.85 = 1.02 
0.55 = 0.66 
0.23 = 0.28 
Mean 
Interval. 
508.55 
509.64 
Correc- 
tion for 
Arc. 
+ 1.14 
+0.34 
Reduc- 
tion to 
36’. 
-1.47 
-1.49 
Corrected 
Vibrations 
at 36’. 
86313.25 
Gauge 3.29 
86313.16 
Gauge 3.84 
86313.20 
The air was then admitted, and the following observations made the next 
morning'. 
