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 veiy 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 apparatxis more suitable than the present to investigate the ratio 

 in which it is possessed by them, could scarcely be devised : and the pendulum, 

 in addition to its many important and useful purposes in general physics, may 

 find an application for its very delicate, but, mth 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. 17th. — Clock gaining 4™ 14'.38. Observer Mr. Taylor. 



o.S 

 Is S 



Thennometcrs. 



Stantlard 

 Barom. 



Disapp. Rc-app. Coincidence, 



Arc registered and 

 true Arc. 



Mean 

 Interval. 



Correc- 

 tion for 

 Arc. 



Reduct. 

 toS6\ 



Corrected 



Vibration* 



at 36°. 



E.S 



I.. Q 



44.5 44.3 



29.70 

 29.7! 



53 09 

 1 18 

 9 28 



53 15 

 1 24 

 9 34 



53 15 

 1 25 

 9 35 



53 24 

 1 34 

 9 44 



' h m 8 

 23 1 21.67 



2 1 29.17 



DiT. o 



0.985 = 1.18 



0.305 = 0.37 



:>491.25 



+ 0.89 



+3.35 



86305.82 



43.95 



29.705; Capill. + 0.019; Reduction to 32° — 0.039; = 29.685. 



86305.82 



