18 Professor Cleveland Abbe, M.A. [Jan. 2%, 



but the very important convection of heat up to the surface of the 

 lakes and oceans ; (12) the consumption of heat in the evaporation of' 

 water and snow. 



The preceding may not be a complete list of the items to be 

 considered, but suffices to show the complexity of the problems that 

 confront the student of our atmosphere ; doubtless most weather 

 predicters attempt to avoid the laborious working out of atmospheric 

 laws by simply utilizing our general knowledge of atmospheric- 

 changes, especially since we have now had ten or twenty years of~ 

 tudy of the weather maps and of the areas of high and low 

 barometer ; but the foundations for a true deductive and philosophical 

 treatment of these problems have already been laid. The motion of a 

 storm centre is a more complex problem and presents more mathe-- 

 matical difficulties than the motion of the moon does to the astronomer, 

 it is in fact only capable of being handled by a mixture of analytic 

 and graphic methods, since no algebraic formula can represent the 

 irregular resistances of the earth surface so simply as can be done by 

 graphic methods, and the same may be said of our thermo-dynamic 

 problems for which graphic methods have also been specially devised.. 

 The last decade has seen important additions to the ranks of those who. 

 are studying the atmospheric problems. I will stop only to mention 

 the memoirs of Sir William Thomson on the stable flow of fluids, of 

 Helmholtz on discontinuous movements in the atmosphere, of Ober-. 

 beck on the general currents and on the whirlwind movements ; : 

 memoirs by Hertz and Berold on the thermo-dynamics of the atmos-- 

 phere ; by Poincare on the atmospheric tides due to the moon ; and 

 even from Japan comes an elaborate paper on atmospheric motions by 

 Diro Kitao, President of the College of Agriculture in the University 

 of Tokio, in which he has elaborated such views as I suppose must 

 have been communicated by Helmholtz or Kirchoff, in their lectures to. 

 their students. But these most recent contributions must not make 

 us forget the work done by the fathers of the new deductive 

 meteorology, and as such we must hold in high esteem two American 

 citizens, James P. Espy and Wm. Ferrel. Espy is frequently quoted 

 as the author of the centripetal theory of storms as opposed to 

 Redfield's circular theory, but the fact is that both of these students 

 were fully aware that in nature the winds blow neither directly 

 towards nor circularly around a storm centre. It was only in the heat 

 of a personal discussion that each was led for a momeut to charac-. 

 terise his idea of storm winds as centripetal and centrifugal respec-. 

 tively ; meaning thereby simply that this was the most prominent 

 feature in his mind. Espy's special claim to our gratitude is his clear 

 appreciation of the thermal processes going on in the clouds. He was 

 always in search of the reasons why, and it was a gnat step forward, 



