154 SCIENCE PROGRESS 



computing orbits for such systems as show orbital motion : a bibliography of the 

 literature on the subject is added for the use of those desirous of pursuing the 

 the matter further. Chapter V, on the " Radial Velocity of a Star," is written by 

 Dr. J. H. Moore, again from practical experience, and deals with the determination 

 of radial velocities with the aid of the spectroscope. In the following chapter the 

 methods of computing the orbits of spectroscopic binaries are explained. Both 

 in this chapter and in Chapter IV numerical illustrations are included, so that the 

 method used may be made clearer. In Chapter VII the much more difficult 

 problem of determining the orbits of eclipsing binary stars is dealt with : the author 

 has copied extensively from the writings of H. N. Russell and Harlow Shapley on 

 this subject, and their treatment of it could not be bettered. In Chapter VIII are 

 collected together the results derivable from the known orbits of visual and 

 spectroscopic binary stars, which are summarised in two useful tables at the end of the 

 book. The following chapter gives a fairly detailed account of the binary systems 

 of more particular interest whose orbits have been well determined. In Chapter 

 X is given a statistical study of the visual binary systems in the northern sky. 

 The information contained in this chapter and'Chapter VIII contain the data at 

 present available which must form the basis of any discussion of the origin of 

 binary systems ; the various theories of their origin which have already been 

 proposed are summarised in Chapter XI. The mathematical treatment of this 

 branch of the subject has been somewhat neglected in the past, though some 

 important papers by J. H. Jeans have recently appeared and form a valuable 

 contribution to it. 



Mr. Aitken is to be congratulated on a lucid, well-written book which is a 

 valuable contribution to astronomical literature. 



H. S. J. 



A Treatise on the Sun's Radiation and other Solar Phenomena. By Frank 

 H. Bigelow, M.A., L.H.D. [Pp. x + 385, with 44 figures.] (New York : 

 John Wiley & Sons, Inc. ; London : Chapman & Hall, Ltd. 1918. Price 

 23s. net.) 

 This volume is a continuation of the author's meteorological Treatise on Atmo- 

 spheric Circulation and Radiation which was published in 191 5. In that volume 

 an attempt was made to work out a system of dynamics for the terrestrial atmo- 

 sphere which should be capable of representing the observational data provided by 

 balloon ascents. Owing to the circulation and radiation in the atmosphere, the 

 assumption of static adiabatic conditions is naturally far from the truth, and Prof. 

 Bigelow proceeded to derive a system of equations in which the specific heats 

 and gas-constants were not assumed to remain constant. 



In the present volume an attempt on somewhat similar lines is made to explain 

 the phenomena of the sun's atmosphere. We do not propose to discuss in detail 

 the amount of success attained by the author in attempting to explain the many 

 solar phenomena brought under review. It is necessary, however, for the reader 

 of the volume to bear in mind that the system of dynamics proposed by the author 

 is not only revolutionary in character but is entirely without support from direct 

 laboratory experiment. Its acceptance would involve the entire recasting of 

 many of our physical ideas, and we doubt whether the author does not tacitly 

 introduce more difficulties than he attempts to explain. Some of its consequences 

 are the variabilities of the gas constant, of Planck's quantum h, and of Avagadro's 

 Constant. It also requires the temperature at a given level in a gas mixture to be 

 different for the different elements, in fundamental opposition to the kinetic 



