DYNAMIC METEOROLOGY. 391 



(25) General treatises on fluid motion. — To complete our list of recent 

 works bearing directl}^ on the mechanics of the atmosphere, we should 

 include a few general treatises on fluid motion that are specially worthy 

 of the study of meteorologists. 



I do not note any general works by French authors, but have reason 

 to expect such in the near future, judging from the introductions and 

 notes in recent publications by Poincar6 ,Boussinesq, Duhem, and 

 Mathieu. Our list is as follows : 



G. KiuCHHOFF. Vorlesungea iiber niathematische Physik. Mechanik. Dritte Auf- 

 lage. Leipsig, 1883, [Chapters 15-26, or oue-half of this volume, is devoted to 

 fluid motions.] 



A. B. Basse r. A treatise on hydro-dynamics, with numerous examples. Vols, i and 

 II [a third is expected], Cambridge (England), 1888. 



W. S, Besant. a treatise on hydro-mechanics. Fourth edition. Part i, hydrostat- 

 ics. Cambridge (England), 1883. [Part ii, hydro-kinetics, is promised.] 



M. DE Saint Venant. E^sistance des Fluids [edited by Boussinesq]. lustitut de 

 France, Tome xliv. Paris, 1887. 



IV.— THERMO-DYNAMICS OF ATMOSPHERIC PHENOMENA. 



(26) Introductory. — The application of the laws of thermo-dynamics 

 to the movements of the atmosphere was first made in a crude manner 

 by Espy and Joseph Henry before the development of this branch of 

 physics had been attempted by Clausius, Sir William Thomson, and 

 others. The memoir of Thomson in 1861 ; Eeye, 1864 and 1872 5 that 

 of J. H. Lane (American Journal of Science and Arts, July, 1870) ; that 

 of Charles Chambers (see the Meteorology of the Bombay Presidency, 

 1878) ; the short paper by Hann (Z. O. G. M., 1874) ; the memoirs of Prof. 

 William Ferrel (see especially his Meteorological Researches, 1877, 1881, 

 1883, and his Recent Advances, 1885; those of Guldberg and Mohn, 

 1876-'78), and the treatise of Sprung (Meteorologie, 1885), have all of 

 them given analytical expressions for this application of thermo-dyna- 

 mics, so that the whole subject of adiabatic changes should now be 

 familiar to all meteorologists. The works of these authors have now 

 been most admirably sui>plemeuted by two memoirs by Hertz and Be- 

 zold, respectively, who have developed graphic methods that render the 

 entire process of cooling and warming easy of computation and clear 

 of comprehension, as also very expeditious. 



The memoir of Hertz is confined to the determination of adiabatic 

 changes, but the memoir of Bezold includes the consideration of changes 

 that are not strictly adiabatic, but in which the quantity of heat within 

 a mass of air actually changes by reason of mixtures, precipitations, . 

 and radiations. 



It is evident to the most superficial thought that the quantity of 

 heat within a given mass of air actually is continually in a state of 

 change and that too not only by reason of its gain of heat from the sun 

 by day and its loss b}' radiation at night, but especially by the process 

 of mixture that is continually going on. On the one hand cold and dry 



