METEOROLOGY. 363^ 



series 2, vol. 11, pp. 367-397. The more difficult problem of proving 

 the existence of, and actually finding, those which are orbits of ejection 

 from one body and of collision with another body has now been treated. 

 The cosmogonical applications of these results are to the escape of 

 particles from one celestial mass and their collision w^ith another. 

 Certain of these orbits are the limits of tw^o families of periodic orbits. 

 They are, therefore, important in the problem of determining the 

 relations among the various classes of periodic orbits. It is shown in 

 this investigation that infinitely many distinct orbits of ejection and 

 collision exist and a large number have been computed. 



(4) Periodic orbits of the problem of three bodies. — In attempting to 

 make a complete study of the periodic orbits of the restricted problem 

 of three bodies and of the relations among them, there has been found 

 reason for suspecting the existence of many new families. Ten new 

 families of these orbits have been shown to exist by actual calculation. 

 The computations, which required the tracing of 156 orbits by mechan- 

 ical quadratures, were made by Mr. W. L. Hart, without whose efficient 

 assistance so much could not have been accomplished. 



METEOROLOGY. 



Bjerknes, V., University of Leipzig, Leipzig, Germany. Preparation of a 

 work on the application of the methods of hydrodynamics and thermody- 

 namics to practical meteorology and hydrography. (For previous reports 

 see Year Books Nos. 5-12.) 



During the past year the preparatory investigations for the working 

 out of the third volume of "Dynamic Heterology and Hydrography" 

 have been continued in different directions. Messrs. Hesselberg and 

 Sverdrup have provisionally carried to an end their investigations on 

 the friction in the atmosphere, and a preliminary communication on. 

 their results is contained in Mr. Hesselberg's paper, ''Die Reibung in 

 der Atmosphare." Important progress in other directions is marked 

 by Hesselberg's paper on the motion of the air in the level of cirrus; by 

 Sverdrup's paper on extent sheets of inversion in free atmosphere; and 

 by papers pubHshed by Hesselberg and Sverdrup conjointly on the 

 influence of the mountains on the motion of the air along the earth's 

 surface, and on fields of acceleration in case of the simplest air-motions. 



The Geophysical Institute of the University of Leipzig has con- 

 tinued the issue of its publications, Series I, "Synoptische Darstel- 

 lungen Atmospharischer Zustande," which are worked out according 

 to the methods developed in parts I and II of the previously mentioned 

 work. Students are also instructed at the Institute in the use of these 

 methods, and are taking up meteorological investigations in which, 

 they come into application. 



The steps taken in the past year by the U. S. Weather Bureau and 

 by the Meteorological Office of London to publish weather charts on 

 which pressure is expressed in c.g.s. units will greatly facilitate the more 

 general use of these methods. 



