210 Scientific Intelligence. 



the present attainment in various branches of science. It con- 

 tains a general account of the composition of the atmosphere; 

 a study of its various properties and phenomena and an explan- 

 ation of the principles of weather prediction. It is obviously 

 a book of information for the interested reader rather than a 

 treatise for the more serious student. p. e. b. 



8. Etude sur Le Systems Solaire; by',P. Reynaud. Pp. xiv, 

 82. Paris, 1919 ( Gauthier-Villars et Cie). — Volumes of obser- 

 tions upon physical and astronomical phenomena are added to 

 our collections each year, but in spite of all the material little 

 progress is being made in coordinating it and deducing the laws 

 which govern the phenomena. The first statement of a law 

 will usually appear in some empirical relation. There was a 

 time when Kepler's Laws and Mendeleeff's Periodic Law were 

 simply empirical. The former have now a sound dynamical 

 basis, and the latter is fast developing from the theory of atomic 

 structure. The study of Dr. Reynaud is a commendable attempt 

 to discov(n' whether any relation can be found to describe the 

 location of the planets in the solar system and the disposition 

 of tlie satellites about a planet. Bode's law, despite its success- 

 ful prediction of the orbits of the asteroids and Uranus, could 

 not survive its failure in the case of Neptune, and has been 

 relegated to the mathematical curiosities. Reynaud considers 

 that since the evolution of any planet and its satellites has 

 followed the same laws as the evolution of the solar system 

 there must be some analogy in the spacing of the members of 

 the system, and he works out some rather striking relations or 

 at least coincidences. By arranging the planets in two groups, 

 between which the asteroids form the dividing line, it may be 

 seen that the distances from the sun in the first group fall 

 approximately into the suite 1, 2, 4, 6, 8 while those of the 

 second have 30 times the same numbers except that the place 1 

 is vacant in the first series and the place 30 X 8 in the second, or 

 we may assign to these places the hypothetical planets Vulcan 

 and Pluto. Now by introducing L = 26.25 million kilometers, 

 the lower limit for any possible planet, and D = 1.41 the specific 

 gravity of the sun, our author finds that the distance of any 

 planet may be expressed by a formula of the form L D"" where 

 m takes on integral values. The success of such a formulation 

 may best be judged by the following table in which the distances 

 are in million kilometers : 



Calculated 





Observed 





26.25 X 1.41 = 



37.0 



Vulcan 



? 



26.25 X (1.41)2 =: 



52.2 



Mercury perihelion 



46.0 



26.25 X (1.41)* = 



104 



Venus 



107 



26.25 X (1.41)5 = 



146 



Earth 



147 



26.25 x(1.41)« = 



206 



Mars 



206 



26.25 X (1.41) « = 



410 



Asteroids 



411 



