Chase.] O/O [Nov. 4, 



range ; r, the virtual radius of daily inertia, 88400''' ^ -^ 2 ; t^, tlie radius 

 of annual inertia, Earth's semi-axis major. 



105. TU St. Helena Test. 



The most extensive and satisfactory intertropical observations that appear 

 to have been published, are those of Gen. Sabine, at St. Helena, in latitude 

 15057'S. Ganot'sformula,^ = 32.174(l — .00356COS. 3^), gives ^ = 32.104, 

 and r = 864002 ^ 16.052 ~ 5280 = 23694600 miles. The mean of five 



years' observation gives e = .067 in. ; e^ = .135 in. ; r^ = -^ = 92188400 



miles. Tliis differs by less than | of one per cent, from the greatest value 

 that seems likely to result from the final discussion of the observations of 

 the last transit of Venus, and by less than ^ of one per cent, from the result 

 that has been indicated by some of the recent English discussions. The 

 simplicity of this relation, in the case of our planet, is perhaps due partly 

 to Earth's position at the centre of condensation in the solar system. 



106. Gaseous Diffusion. 



Doebereiner, in his researches on spongy platinum, accidentally used a 

 jar which had a slight crack or fissure. He was surpi'ised to find that the 

 water of the pneumatic trough rose into the jar two and two-third inches 

 in twentj'-four hoars, although there had been no sensible change in the 

 height of the barometer or the heat of the room. This observation led 

 Graham (Chemical and Physical Researches, p. 44; Phil. Blag., and Pogg. 

 Ann., 1833), to the experiment from which he deduced his law of gaseous 

 diffusion : "The diffusion or spontaneous intermixture of two gases in 

 contact is effected by an interchange in position of indefinitely minute vol- 

 umes of the gases, which volumes are not necessarily of equal magnitude, 

 being, in the case of each gas, inversely proportional to the square root of 

 the density of that gas." He subsequently (BesearcJies, p. 88 ; Phil. Trans. 

 1846, 1849), showed that this was a result of diffusive velocities varying 

 "inversely as the square root of their densities, " referring also to "the 

 theoretical law of the passage of gases into a vacuum, according to the 

 well-known theorem that the molecules of a gas rush into a vacuum with 

 the velocity they would acquire by falling from the summit of an atmos- 

 phere of the gas of the same density throughout ; while the height of such 

 an atmosphere, composed of different gases, is inversely as their specific 

 gravities. This is a particular case of the general law of the movement of 

 fluids, well established by observation for liquids, and extended by anal- 

 ogy to gases." These views involve all the consequences of equality of 

 vis viva, in chemical as well as physical actions and reactions, and they 

 indicate the direction in which we may still look hopefully for an exten- 

 sion of our knowledge of chemical physics. 



