46 The Principles of Fruit-growing 



stream. In very gradual slopes, the ameliorating influence 

 of the water usually extends farther, but it is likely to be 

 less marked than on the lower parts of abrupt slopes. In 

 all these cases, the limit of the boundary of the area is 

 determined largely by two factors,^ — ^the distance from 

 the water, and the elevation above it. 



Tarr, after studying the local geography of the Chau- 

 tauqua grape country, makes the following observations 

 on the amehorating influence of Lake Erie, and the remarks 

 will apply to most other bodies of water: "The lake is a 

 great modifier of climate. In the spring, by reason of the 

 low temperature of its waters, it holds back the vegetation, 

 and this tends to keep it behind the ordinary frosts. Its 

 very presence checks frosts by moderating the temperature 

 of the neighboring air. In the summer, the water tends to 

 cool the air of the day and to keep the nocturnal tempera- 

 ture fairly high. During the fall, the water has been 

 warmed by the summer sun, and the influence of this 

 warm body of water lengthens the growing season and 

 tends to keep off the early autumn frosts. There are 

 many other influences, but nothing of importance can be 

 stated, excepting on the basis of a careful study extending 

 over several years. The lake breeze of the day must 

 moderate the daytime temperature; and the land breeze 

 of the night may, in some cases, so keep the air in motion 

 as to prevent frosts. That there is a marked influence upon 

 climate as a result of the peculiar conditions of topography 

 and neighborhood of water, is evident at the very first. 

 Sketch maps show that the mean annual rainfall is greater 

 on the escarpment than on the lake plain, and that the 

 mean annual temperature of- the hills is lower than that 

 near the lake." 



The particular influence exerted by the water over 



