LOCAL CLIMATOLOGY. 



95 



thing for the time being as sensible heat. Hence for this cause alone the 

 temperature in the presence of an extensive vegetable growth would not 

 be so hot as if there were no such growth, and the country were a sandy 

 or rocky desert. 



In the winter, however, when the ground is covered with snow, the 

 heat is reflected back at once to a large extent, and does not penetrate 

 the mass ; nor yet, in its immediate influence, does it appear to produce 

 much effect upon the tempef-ature of the atmosphere into, or rather 

 through, which it passes. Hence the temperature, as indicated by a 

 thermometer, will be colder than if there were no snow ; and besides 

 this, the snow is always wasting away by evaporation, even in the coldest 

 weather. This process is much accelerated by the direct rays of the sun, 

 and the more so, the hotter those rays may happen to be ; consequently 

 a large part of the heat is absorbed, in the process of evaporation, as 

 " heat of liquefaction " for the melting snow. 



But besides this, and beside the general influence of our inland lake 

 system, which, as I have already said, extends to all localities in this 

 region, I have no doubt that the immediate proximity of our lake — the 

 Seneca — is manifest in the phenomenon under consideration. The lake 

 is very deep, is never very warm in summer, never freezes over far from 

 the shore, and seldom (not more than once in about five years on the 

 average) accumulates ice enough, even about the docks, to interfere with 

 the steamboat landings. 



As confirming and illustrating my position, I introduce statistics derived 

 from observations taken at Canandaigua. The comparative physical posi- 

 tion of the two places is indicated as follows : 



Locality. 



Latitude. 



Longitude. 



Height above 

 sea, in feet. 



Canandaigua . 

 Geneva 



42.50 



42.52 



77.15 

 77.20 



(about) 590 

 567 



the only noticeable difference being 13' of longitude, or a few miles west 

 and east. 



Canandaigua is situated about one mile north of Canandaigua lake, and 

 about 100 feet above its surface ; but the lake is much smaller than the 

 Seneca, and at a distance of some three miles from its foot trends west- 

 ward around a promontory that rises between the village and the main 

 body of the lake. The lake freezes early in the winter or late in the 



