65 



tion in islands, which may occur as well for a considerable distance in- 

 land from the margin of the water. The presence of this stratum of 

 air is evidenced by the absence of light frosts during late fall, and the 

 freshness of vegetation as far as the heated atmosphere extends, while 

 immediately beyond its influence a wintry aspect prevails. 



In this case the cause of exemption from cold also prevents the for- 

 mation of dew, and is so far favorable to the healthy growth and free- 

 dom from mildew of the grape. 



Again, in districts where hills and valleys are closely and distinctly 

 defined, there are, at certain elevations on the hillsides, a zone 

 or belt where dews are not known and where frosts are modified. The 

 width of this belt varies according to the degree of cold and, to some 

 extent, configuration of surface, but it exists in all countries that are 

 traversed by high mountains and deep valleys. Several years ago, 

 when collecting data on this subject, a correspondent in Matjon County, 

 North Carolina, wrote as follows: 



The frost line is not permanently fixed at any particular height on a mountain, but 

 takes a higher or lower range according to the degree of frost that produces it ; 

 within the space of 11 years its maximum height has been 300, and its minimum 

 height 125 feet, vertical. Another fact ascertained is that there is no fixed dew line 

 on our mountain sides, but that it gradually abates as you ascend, and at the height 

 of 300 feet the dew is too Ifght to produce either rot in the berry of the grape- 

 vine or mildew on its leaves. Hence we understand why the thermal zone is both 

 warm and dry. I will not venture to say that the grape will never rot within the 

 limits of that zone, but I can say that the Catawba grape is altogether unreliable 

 when planted in our low valleys, but where the vines are growing on the slopes of 

 the mountains they have not failed to ripen their fruit for more than 30 years, whether 

 the season was wet or dry. It is a fact that all attempts to cultivate the grape in 

 our low damp valleys have utterly failed, the plants invariably being destroyed by 

 mildew on the leaves, while the few vines that grow upon the small farms lying 

 high up on the mountain sides have ever matured their fruit in the greatest perfec- 

 tion. 



In view of these facts, I say confidently that any well-conducted effort at grape 

 culture will succeed, whether it be upon the slopes of our Alleghauies or upon the 

 mountain sides that skirt the valleys of more northern States, and all that is required 

 to insure success is to ascertain where this warm belt is, and to plant the vine within 

 its limits. 



In the report of the Department for 1867 mention is made of the 

 great success in grape culture in the region near Harnrnondsport, Steu- 

 beu County, New York. Here the Catawba and other late grapes ma- 

 ture and reach remarkable perfection, taking the latitude into consid- 

 eration. These vineyards are mostly on hillsides extending for several 

 hundred feet above the valley and surface of Keuka Lake. The soil is 

 a drift formation, and the surface is thickly covered with loose shale. 

 The marked adaptability of this locality for grape culture may be 

 attributed to its elevation and nature of the soil. The general elevation 

 of the land prevents the deposition of heavy dews, and as it is supple- 

 mented by the heat absorbed during the day by the abounding stony 

 Surfaces, mildew is unknown, and the growth proceeds unchecked until 



