488 



AGRICULTUR^VL REPORT. 

 Quantities of water evaporated in inches of depth. 



The first series of quantities above given for Whitehaven, in one of the most 

 humid districts of England, was carefully observed from 1843 to 1848 by evap- 

 orating from a shallow copper vessel one and a half inch deep, filled daily 

 and protected from the rain. The annual fall of rain at this place was 42.25 

 inches, and the amount evaporated was in excess of the rain fall ; but generally 

 jnuch less is evaporated than falls each year. In the United States the evapora- 

 tion is always much greater from a vessel thus supplied and protected from 

 rain than the actual depth of rain precipitated, and we may assume the 

 evaporation from a reservoir surface, when compared with the quantity of rain to 

 be, duruig the summer months, as two to one, or twice as great. The absorbent 

 power or capacity of the air of England is thus strongly contrasted with that 

 of the United States, the air of the former, under similar conditions, taking up 

 but half the quantity evaporated in the latter. And though the case cited 

 may be an extreme one, and not fully illustrative of the conditions of 

 atmospheric capacity for moisture as it exists in France and Germany, yet the 

 difi"erence will be found one of degree merely, and the average dryness of the 

 American air will prove still largely in excess of that of western Europe. 



That it is to excessive atmospheric humidity, alternating with aridity, and 

 both combined with high temperatures, that we must ascribe our failure to 

 cultivate the European wine grape, is attested by the success with which our 

 American varieties are grown under circumstances which combine proper 

 temperature with more uniform humidity, and our ill success when we attempt 

 the extensive cultivation of even our native sorts iu localities which are subject 

 to the above extremes. In the districts where the Isabella and Catawba are 

 largely and profitably grown, the vineyards are either surrounded by water or 

 so influenced thereby as to enjoy a comparatively humid atmosphere combined 

 with more moderate summer maxima and long continued autumn heat. Thus 

 the Croton Point vineyards, of Dr. R. T. Underbill, are nearly surrounded by 

 water. The vineyards on Kelley's island. Lake Erie, where the Isabella and 

 Catawba of superior quality are grown very extensively, and with almost 

 uniform success from year to year, are directly under the influence of the lake 

 waters, whose equalizing effects upon the humidity of the air upon its borders 

 must be as marked as is that it exerts upon the mean temperature of summer 

 and its lengthened autumn.* 



* An illustration of the influence of the lake in regulating the phases of the vegetation in the 

 region round about may be found in the following, furni.slied by George 0. Huntington, an 

 rntelligent meteorologi.st and vine culturist, of Kelley's island. He has observed that the Isa- 

 bella and Catawba grapes are uniformly in full bloom on the 2(Jth of June, and accounts for 

 this remarkable unifonnity by ascribing it to the influence of the lake, the temperature of 

 . whose waters scarcely vary at this .season, having, on the 30th of June, exhibited a mean of 

 sixty-nine degrees, Fahrenheit, through a series of five years. 



