New York Weather Bureau. 463 



An uuibr'oken record of temperature has been kept at Ooopers- 

 town, N. Y., since 1842; a standard thermometer favorably 

 exposed being used after 1853. Mr. G. Pomeroy Keese, the 

 oibiserver, gives, as the highesti tempera'tuTe of the entire period, 

 96 degreeis on July 3, 1868, and as the lowest, -30 degrees O'u 

 February 7, 1855, and January 24, 1857. 



Variability of Temperature. 



This important climatic element may ibe measured by the aver- 

 age difference which oibtains ibetween the mean temperature of 

 successive days, a method wlhich eliminates the nearly constant 

 diurnal variation. General A. W. Greely gives in " American 

 Weather" the values thus derived for representative stations in 

 New York and other States during January, the imonth which 

 in most eases has the maximum variability : 



Table 11. Variability of Temperature. 



For the Great Lake Region the mean variability in January is 

 7.4 degrees. 



Foir the eastern central section -the mean variability in January 

 is 7.6 degrees. ' 



For the Atlantic coast region the mean variaibility in January 

 is 6.5 degrees. 



During the same month the variability on the coast of Gali- 

 fornia is 2 degrees; on the south Atlantic and Gulf coasts 6 

 degrees; in the central statesi of the Mississippi valley from 8 

 degrees to 9 degrees; and in the region of the upper Missouri 

 valley from 9 degrees to 10 degrees. The greatest variability 

 which has ibeen found within the United States is 11 degrees at 

 Portland, Me. 



T*he following table exhibits the varia:bility of temperature in 

 various partis of the State in a somew'hat different manner from 

 the above: 



