l\ Waldo— Contributiotis to Dynamical Meteorology. 281 

 u compared with the more finished analysis of the present 



ideas of fluid and vortex motion. The works of (iuldborg and 



M..hn are also referred to: the author also calling special 



attention to the estimate Sprung has given, in his " Lehrbuch," 



these writers, and particularly of Ferrel's work. Next he 



es an outline of the methods used in hie own paper (No. 6) 



and explains with greater clearness the part friction plays in 

 the whole matter of fluid motion. Finally, he gives a rough 

 chart, on the Mercator's projection, of the air currents for the 

 lower layers as deduced by his theory. 



.V,,. !>. — Professor von Helmholtz, who has done so much 

 for the advancement of other hranches of physics, has at last 

 en some attention to a problem in every way worthy of his 

 consideration, viz: Atmospheric motions. The author's well 

 known investigations on fluid motion have been used as a basi> 

 for other contributors to work from, but I believe he has him- 

 >elf published only one other paper, and that of a popular 

 nature, which deal's with a specially meteorological topic. 



In the present paper the author treats: § 1, The influence 

 of friction on the great circulations of the atmosphere; §2, 

 Rings of atmosphere having different temperatures and rota- 

 tion' due to the equilibrium; £ 3,* Adjacent layers in equilib- 

 rium, and having different values of & and Q\ §4j Gradual 

 changes of equilibrium through friction and warming up. 



By aid of the potential, the author derives the equations of 

 fluid motions taking into consideration the friction. The inte- 

 ntion of these equations cannot be accomplished until certain 

 constants have been determined. A very neat comparison is 

 made of the two methods of determining the friction constant, 

 viz : in the laboratory, and in nature. There are not data for 

 the latter for high elevations but some valuable ideas are given, 

 which the theory shows must hold good. These relate to 

 change of friction with distance from the ground, differences 

 of pressure and differences of temperature. The author then 

 applies his reasoning to several rings of atmosphere encircling 

 the globe at various latitudes, but finds that other influences 

 must be considered, before the observed facts can be explained. 

 In g 2, the method of determination of the calm belt, toward 

 which the " pressure'' increases both from the pole and from 

 the equator, is of great importance. In §3, the conditions of 

 equilibrium, as determined by the heat capacity of the differ- 

 ent layers, are worked out in a very general way ; and the form 

 of the layers is shown for various cases. The position is also 

 given of the layers in the case of continual change of the 

 velocity of rotation with the heat capacity. The ^4 contains 



* i? is the temperature of the air under pressure p . fl is the moment of rota- 

 tion (which remains constant under certaio assumed conditions). 



