214 
CAPTAIN SABINE ON THE REDUCTION TO A VACUUM 
No. of 
Coincid. 
Therm. 
Barom. 
Times of 
Arc registered 
and True Arc. 
Mean 
Interval. 
Correc- 
tion for 
Arc. 
Reduc- 
tion to 
72°. 
Corrected 
Vibrations 
at 72°. 
Disapp. 
Re-app. 
Coincidence. 
1 
12 
26 
O 
73.6 
73.0 
72.5 
inch. 
29.90 
29.86 
m s 
38 14 
46 10 
13 00 
m s 
38 20 
46 21 
13 23 
h m s 
5 38 17 
6 46 15.5 
8 13 11.5 
0 / o / 
2 02 = 1 44 
1 15 = 1 04 
0 43 = 0 36 
s 
370.77 
372.57 
+ 3.06 
+ 1.11 
s 
+ 0.55 
+ 0.31 
85937-37 
85937-44 
73.03 
29.88; Index + 0.066; Reduction to 32° — 0.117 ; = 29-829. 
85937-40 
The glasses were then removed, and the pendulum raised on the Y’s ; in 
which operation it was observed that it had not quitted its place during the 
experiments, in which it had been twice set in motion and twice stopped by 
the wire which passes through the stuffing-box. The pendulum was then re- 
moved, and the horizontality of the planes examined and found perfectly correct. 
The vibrations in air, before and after those in the rarefied medium, were as 
follows : 
In the morning, before the vibration in') B . a „ 7 KA 
the rarefied medium J ' 
In the evening, after the vibration in 
the rarefied medium .... 
} 
85937.40 ; 
Barom. 29.861 
Barom. 29.829 
Mean . . . 85937-47 ; Barom. 29.845 
The vibrations in the rarefied medium, re ~l (35944 35 
duced to the same temp, as those in air . . J 
Gauge 7-08 
Whence there appears, as the result of this experiment, a difference of 7-38 
vibrations per diem, corresponding to a difference of atmospheric pressure of 
22.765 inches: the temperature of the air of full pressure being 72°.01 ; and 
that of the rarefied air 72°-5. 
The indications of the thermometer in the rarefied medium have been in- 
creased 0°.7, to compensate the effect produced on the thermometer by the 
removal of the full pressure of the atmosphere. It has been noticed, that on 
the pump being worked, the thermometer, which previously stood at 71°-4, fell 
to 70°.7, which it indicated when the pressure was reduced to 7 inches. The 
converse took place when the air was re-admitted. To ascertain whether this 
effect was rightly ascribed to the removal of the pressure of the atmosphere on 
the exterior of the ball and tube of the thermometer, the following experiment 
