712 



SCIENCE. 



[N. S. Vol. II. No. 48. 



earth's surface, or as two areas of high pres- 

 sure flowing toward each other must lift up 

 the lighter air between them and set it into 

 cyclonic rotation, we must, therefore, recog- 

 nize the general conclusion that Espy's 

 aspiration cyclone as developed by Ferrel 

 is not the only form of cyclone, but that 

 those due to descending cold air and, there- 

 fore, having the general circulation of the 

 atmosphere as their fundamental cause are 

 equally entitled to consideration. 



To this last and latest development from 

 the theoretical side I need only add that 

 the study of the motions of the clouds has 

 enabled me to assert confidentlj' that there 

 is no form of motion known to the student 

 of the mechanics of fluids but what is to be 

 found beautifully illustrated in some impor- 

 tant phenomenon of the atmosphere. I 

 may give one illustration of this statement. 



All have seen the beautiful standing 

 waves on the surface of a httle stream of 

 water flowing over a rocky bed. The the- 

 oretical studjr of these waves began with 

 Bidone early in this centurj^ and has been 

 especially prosecuted by Bazin and Boussin- 

 esq in France and Sir William Thomson in 

 Scotland. Precisely similar waves must oc- 

 cur in the atmosphere, but can only become 

 visible to us bj^ the formation of clouds at 

 the summit of each wave if the air rises 

 high enough. Invisible standing waves 

 exist over our heads all the time. It was my 

 good fortune to make an extensive series of 

 observations on a remarkably well devel- 

 oped system of standing waves capped 

 by clouds, which perpetually extend from 

 the summit of Green Mountain, on the 

 Island of Ascension, to the leeward for a 

 hundred miles under the influence of the 

 steady southeast trade wind. These become 

 invisible when the air becomes a little cooler 

 or dryer, and consequently they actually 

 disappear every night only to reappear as 

 regularly every day. 



But I need not dwell any longer on the 



relations of the theoretical and the actually 

 observed motions of the atmosphere. Our 

 interest in the meteorological or dynamical 

 theories and their appHcation to the atmos- 

 phere is not inferior to our interest in any 

 other physical science. 



The possibility of making accurate long- 

 range pi'edictions of the weather and the 

 seasons is recognized as an ultimatum that 

 should fire the zeal of everj^ young phy- 

 sicist. 



Meteorology has advanced far beyond the 

 stages of observation and generalization. 

 It has had its Newton, Laplace, Dove, 

 Espy, Forrel, Oberbeck, and Helmholtz and 

 Thomson. As an application of mathema- 

 tical physics it outranks all other branches 

 of science in its universal importance and 

 its difficulty. Why should it not be recog- 

 nized as worthy of study in our univer- 

 sities ? 



COURSE OF INSTRUCTION IN METEOROLOGY. 



The following courses in the Department 

 of Meteorology are designed to give a com- 

 plete review of the present condition of 

 that science, and are therefore necessarily 

 extended through four years ; but the series 

 of lectures is so arranged that each of the 

 four divisions is complete within itself; 

 each course presents a view of a branch of 

 the subject such as may be desired by a 

 large number of students who need this in- 

 formation in connection with other branches 

 of knowledge to which thej^ are specially 

 devoting themselves. 



Students who intend to take the degree 

 of Ph. D. in meteorology, and who there- 

 fore make this the major subject in connec- 

 tion with several other minor courses, must 

 pursue the whole four years' course. Those 

 who merelj' desire to understand observa- 

 tional meteorologj' will probably find the 

 first year's course sufiicient. Those who 

 desire to do original work in climatological 

 study should also take the second year. 



