PHYSICS OF THE GLOBE. 119 



the transparency of the waters of lakes in winter and sum- 

 mer. The theory is based upon the thermal stratification of 

 the water during the summer, and its non-stratification dur- 

 ing the winter. _ 



THE ATMOSPHERE. 



INSTITUTIONS, OBSERVERS, GENERAL TREATISES, ETC. 



The Smithsonian Institution reports the continuation of 

 work on the new edition of the " Rainfall Tables for North 

 America." It has also printed the observations of Professor 

 Caswell, from 1860 to 18*76, in continuation of his previous 

 work from 1830 to 1860. This record shows a steady in- 

 crease in the rainfall at Providence. Work has also been 

 done on the maximum and minimum temperatures, and on 

 the preparation of a work on thunder-storms. 



An exhaustive memoir on the Meteorology and Ocean 

 Physics of Behring Sea and Alaska has been prepared by 

 W. H. Dall for the Coast Survey, but is not yet published. 



The report of the Chief Signal Officer for June 30, 1878, 

 enumerates, among other features in the history of the Army 

 Weather Bureau, the fact that its permanent organization 

 has been established as embracing 150 sergeants, 30 corpo- 

 rals, and 270 privates. One hundred and forty-seven first- 

 class stations and 24 second-class or sunset stations report 

 telegraphically, and about 800 stations report by mail. Tel- 

 egraph reports are received, as usual, from Canada and the 

 West Indies. The average time elapsing between the moment 

 of simultaneous observation throughout the country and that 

 at which the resulting prediction is issued from the Central 

 Office is one hour and forty minutes. The average percent- 

 age of verifications is 84.4. The percentage for the state of 

 weather only, omitting the predictions for the barometer, 

 thermometer, and wind direction, is 88.3. Cautionary storm- 

 signals are displayed by day and night at 57 stations. A dis- 

 tinction is made between the cautionary signal for high winds 

 in general and that for winds blowing: offshore. Of the to- 

 tal number of signals displayed, 75.9 per cent, have been veri- 

 fied. Special display-stations have been established at about 

 30 subordinate stations. Weather maps and bulletins have 

 continued to be exhibited at all public places of business and 



