232 
CAPTAIN SABINE ON THE REDUCTION TO A VACUUM 
ascribed to accidental error in the experiment, particularly as repetition pro- 
duced results almost identical. May it not indicate an inherent property in the 
elastic fluids, analogous to that of viscidity in liquids, of resistance to the 
motion of bodies passing through them, independently of their density ? a pro- 
perty, in such case, possessed by air and hydrogen gas in very different degrees ; 
since it would appear from the experiments, that the ratio of the resistance of 
hydrogen gas to that of air is more than double the ratio following from their 
densities. Should the existence of such a distinct property of resistance, varying 
in the different elastic fluids, be confirmed by experiments now in progress with 
other gases, an apparatus more suitable than the present to investigate the ratio 
in which it is possessed by them, could scarcely be devised : and the pendulum, 
ia addition to its many important and useful purposes in general physics, may 
find an application for its very delicate, but, with due precaution, not more 
delicate than certain, determinations, in the domain of chemistry. 
Experiments IX, X, XI. 
These experiments are classed together, their object being the same, and 
distinct from any of the preceding. It yet remained to be established by ex- 
periment, that with a free communication between the interior of the apparatus 
and the external air, the pendulum, vibrating within the glasses, made the same 
number of vibrations as if the glasses had not been present. For this purpose 
the foot screws of the apparatus were simultaneously lowered, so as to detach 
the upper of the three middle glasses from the suspension piece. The glasses 
could then be removed, and replaced, in successive observations ; the appa- 
ratus being in the same state, with the glasses replaced, as in the observation 
in air in the preceding experiments, with the exception of a disjunction of less 
than the tenth of an inch between the upper glass and the suspension plate. 
Exp. IX. Feb. 17 th. — Clock gaining 4™ 14 s .38. Observer Mr. Taylor. 
c 
Thermometers. 
Standard 
Barom. 
i 
4 
o 
o 
inch. 
43.4 
43.5 
29.70 
44.5 
4 4.3 
29.71 
1 
j 43.95 
29.705 
Times of 
Disapp. 
Re-app. 
Coincidence. 
m s 
m s 
53 09 
53 15 
/ h ms 
1 18 
1 25 
> 23 1 21.67 
9 28 
9 35 
) 
53 15 
53 24 
1 24 
1 34 
V 2 1 29.17 
9 34 
9 44 
•> 
Arc registered and 
true Arc. 
Mean 
Interval. 
Correc- 
tion for 
Arc. 
Reduct, 
to 36 \ 
Corrected 
Vibrations 
at 360. 
1 
2 
3 
23 
2 5 '2 | 24 
V ■ — 
•5 J 
■j : — 
S» 
Div. o 
0.983= 1.18 
0.305 = 0.37 
>491.23 
+ 0.89 
+ 3.35 
29.705; Gapill. + 0.019; Reduction to 32° - 0.039; = 29.685. 
86305.82 
86305.82 
