METEOROLOGY. 407 



of M. Eerset's and accepts his results, that about 3 volumes in 10,000 rep- 

 resent the greneral ratio of CO2 in air. The variations through great 

 movements of the atmosphere now require study, by observers placed 

 at many different and distant stations, and the transit expeditions 

 should keep this in view. MM. Miintz and Aubiu's methods are most 

 suitable for this. {Nature, xxv, p. 47C.) 



Berthelot has communicated to the Paris Academy of Sciences an 

 important memoir on the propagation of the waves of explosion as dis- 

 tinguished from waves of sound. An explosion starting in a mixture 

 of oxygen and hydrogen propagates itself at a rate of 28.14™ per second, 

 butthe velocity of sound is 514; he therefore concludes that the explosion 

 wave is not an acoustic wave, but a wave of chemical action, and he 

 attempts to explain its nature on principles suggested by the kinetic 

 theory of gases. {Nature, xxv, p. 44.) 



Sir William Thomson read before the Royal Society of Edinburgh a 

 paper on the thermodynamic acceleration of the earth's rotation. He 

 shows that there must be tides in the atmosphere, and that the line of 

 crests, namely, the maximum of atmospheric pressure, so lies with respect 

 to the line joining the earth's center and the sun's that the couple due to 

 the sun's attraction upon the ellipsoidal mass of air always acts in the 

 direction of the earth's rotation, and therefore accelerates it slightly. 

 {Nature, xxv, p. 380.) 



Stanley has published a volume on experimental researches into the 

 properties and motion of fluids. The author, in writing section second, 

 seems not to have taken advantage of the works of the best modern 

 students on meteorology and the motions of the atmosphere. 



Maj. John Herschel has completed the pendulum experiments recom- 

 mended by the Royal Society, and, having swung one of the original 

 Kater pendulums in India and Europe, and finally in Xew York and 

 Washington, has deposited it with the United States Coast and Geodetic 

 Survey. The latter has, we understand, immediately started it again 

 on its travels in connection with its own most elaborate pendulum work 

 under the direction of Prof. C. S. Peirce. 



Joly, at Munich, has attempted to determine the force of gravitation 

 by means of a delicate balance, from each of whose scale-pans was hung 

 by a wire, at a depth of about GO feet, another pair of pans. A heavy lead 

 ball is brought under one of the lower scale-pans, while a small body 

 can be placed in either an upper or lower pan at will, and thus have its 

 weight determined under the influence of the lead ball and again when 

 beyond its influence. The result of his experiments has given him for 

 the mean density of the earth, 5.G92 plus or minus 0.068, agreeing closely 

 with the results of the torsion balance. (Nature, xxv, p. 137.) 



Tyndall has in a series of brilliant experiments introduced Bell's 

 radiophone as a means of easily deciding the question as to the absorp- 

 tion of radiant heat in its passage through gases and vapors. He finds 

 every observation to completely justify the position he has so long main- 



