VG ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



the year arc given, and the latter is condensed into a mean 

 for each parallel of latitude, whence is deduced the folio w- 

 ino- formula in centigrade degrees: 



*=$.50-1.75 cos. 0-20.95 cos. 20-1.00 cos. 30-2.GG cos. 40 

 (where 9 is the the north polar distance) ; 



whence, by integration, there results the mean temperature 

 of the surface of the southern hemisphere, 4-10.05; and of 

 the northern, 15.30; and for the whole earth, 15.07, a re- 

 sult ao-reeinc: closely with Forbes and Von Waltershausen. 



(4) In a similar manner new charts of isobars, based on 

 the newest data collected by RikatchefF, Hann, Buchan, etc., 

 have been compiled by Ferrel, which, together with charts 

 of the annual inequality, are all upon a polar projection. 



(5) The general circulation of the atmosphere is deduced 

 by reasoning based on the charts and the mechanical prin- 

 ciples previously deduced. 



PRESSURE AND ISOBARS. 



The normal distribution of atmospheric pressure in Eu- 

 rope has been further elucidated in an important memoir by 

 Buys-Ballot, published in the JVederlcmds Jaarbooek. 



Buchan's paper on the diurnal barometric periods, in which 

 he showed the decided influence of the relative distribution 

 of land and water, has not yet been followed by the prom- 

 ised second part. And the conclusion formerly deduced by 

 the present writer still seems to be inevitable i. <?., that the 

 diurnal and annual variations in the distribution of heat and 

 moisture induce corresponding changes in the wind currents 

 and consequently in the barometric pressure, the exact laws 

 of which are contained in the formula? of Ferrel's "Motions 

 of the Winds on the Earth's Surface," though not developed 

 by him with special reference to this interesting point. 



This subject has been recently studied by Chambers, 

 Broun, Belfour, Stewart, and Blanford. Starting with the 

 idea of Kreil and Espy and others, that the expansion of the 

 lower strata up to 10 A.M. is resisted by the weight of the 

 surrounding atmosphere, thereby producing an increase in 

 the pressure at the earth's surface, Blanford seeks to show 

 that, at least in India, the greater part of the barometric ir- 

 regularities result from the transfer of air from land to sea 



