PHYSICS OF THE GLOBE. 75 



and others, according to whom bodies moving on the paral- 

 lels do not deviate to the east or west. This fundamental 

 theorem in the dynamics of the atmosphere was abundantly 

 elucidated in the discussion that was from 1S51 to 1860 fully 

 reported in the Paris Comptes Rendus. The more general 

 law known as Poisson's in France, and in America as Fer- 

 rel's, was applied to the winds of the globe by Babinet, 

 1854, and simultaneously by Ferrel, whose complete memoir 

 marks an important epoch in the development of meteoro- 

 logical science. A very complete review of the literature 

 of this subject, so far as it relates to Baer's Law, is given by 

 Benomi and Schmidt in the Vienna Geog. Mitth. 



It is said that M. Finger, in a memoir on the mathemat- 

 ical theory of the motions of the atmosphere, has demon- 

 strated among other things that the pressure is increased by 

 easterly winds and diminished by westerly winds. 



This latter scientist has enriched meteorology with a mem- 

 oir, which is substantially a second edition of his famous pa- 

 per of 1859, on the motions of the winds on the surface of the 

 earth. This latter paper was too little known among Euro- 

 pean meteorologists until reviewed by Hann, a year ago, in 

 the Zeitschrift of the Austrian Meteorological Society. The 

 present writer, however, in 1865, and especially in 1869, had 

 drawn the attention of certain individuals to this important 

 memoir, and in 1871 quoted it quite freely in the pamphlet 

 of "Suggestions on the Use of Weather Maps" (published by 

 the Army Signal Office, 1st edition, May, 1871) ; while, in the 

 meantime, Professor Everett, in his translation of Deschanel's 

 Philosophy, had spoken of it in terms of highest praise. In 

 fact, the fundamental problems of deductive meteorology 

 were, for the first time, solved satisfactorily in this first 

 edition. Professor Ferrel has simply revised his work in 

 the light of the great mass of accurate data that have with- 

 in twenty years been accumulated by the meteorological 

 writers. The most important new features of the work 

 consist in, (1) the formula for variation of pressure with al- 

 titude when the air is in motion ; (2) the expression for the 

 gradient of inclination of any current of water or air in a 

 section at right angles to its course; (3) a table of mean 

 temperatures over the whole earth, deduced by combining 

 the best modern authorities; tables for January, July, and 



