Geography of the Air. 155 



General A. Von Tillo has determined, by means of the plani- 

 meter^ the distribution of temperature and pressure from Teisse- 

 renc de Bort's charts. The mean pressure over the Northern 

 Hemisphere for January, he finds to be 29.99 inches (761.7 milli- 

 meters), and the temperature 46°.9 (8.3 C.) ; in July, 29,806 

 (758.5 mm.) and 12°.1 (22°.6 C). In Russia he finds an increase 

 of one millimeter of pressure to correspond with a decrease of 

 1°.6 C. in temperature. 



Doberck, after investigation of September typhoons at Hong 

 Kong, attributes their appearance to the relatively low pressure 

 then existing between Formosa and Lyon, 



The valuable and elaborate investigation of American Storms, 

 by Professor Elias Loomis has been completed. Loomis has 

 thoroughly discussed barometric maxima and minima areas as 

 presented by the maps of the Signal Service, from which it 

 appears that these areas are in general elliptical, with the longest 

 axis nearly twice that of the shortest in the high areas, while the 

 difference is less in low areas. He has also investigated the 

 winds relative to baric gradients, thus affording valuable data for 

 proving various meteorological theories. Loomis' researches re- 

 garding the movement of maximum areas verify those which 

 have been set forth from time to time in Signal Service publica- 

 tions ; wherefrom it appears that high areas have a more south- 

 erly movement than low areas. 



Van Bezold has put forth a memoir on thermodynamics, while 

 Helmholtz, Oberbeck, and Diro-Kitso have contributed valuable 

 memoirs on motions caused by gravitation and the varying den- 

 sity of the air. These furnish meteorologists with important re- 

 sults as to the laws of fluid or gaseous motions. It is gratifying 

 to Americans to note that the valuable results obtained, by 

 Ferrel in his many memoirs are confirmed by these later investi- 

 gations. 



Undoubtedly the most important meteorological event within 

 the past year was the discontinuance, on January 1, 1888, of 

 the system of International Simultaneous Meteorological re- 

 ports inaugurated in accordance with the agreement of the con- 

 ference at Vienna in September, 1873. As the charts of storm 

 tracks, based on these observations, have been published by the 

 United States Signal Service one year behind the date of the 

 observations, the completion of this work in printed form for the 

 general public should occur about December 31, 1888. 



