THE CULTURE OF THE GRAPE. 75 



rentlj, too low a temperature at the top of the plant, causing 

 stagnation of the sap. A brisk heat from a flue, or any other 

 artificial means that will give a free circulation to the air 

 throughout the house, and raise it to a temperature near which 

 it has been during the hot weather, will prevent its spread. 

 The cold rain will have reduced the temperature at the roots 

 of the vine, but in a much less degree than that to which the 

 tops have been exposed, so that now the tops are relatively to 

 the roots in a proportionately warmer atmosphere than during 

 the hot weather. It does not appear to me, that want of 

 warmth at the root of the vine is the cause of the difiiculty. 

 These varieties of the foreign grapes which, in the grapery, 

 are now so much affected by this change in the weather, when 

 in the open air, and growing in the same soil, do not suffer in 

 the least from this shanking. It therefore appears evident, 

 that the cause of the difficulty must be looked for in the tem- 

 perature and ventilation of the grapery. And these causes 

 are, in my opinion, too great and sudden changes in the tem- 

 perature, and, perhaps, too great heat at night relatively to 

 V the day. '•—'' 

 ■"■^ A low temperature at night is not injurious to the vine,* on 

 the contrary, it is probably beneficial. But the vine under 

 glass, when the sun is shining, is subject to great heat, which 

 rapidly accumulates, and, on the obscuration of the sun's 

 rays, as rapidly decreases. Here is the cause of the trouble : 

 vines in the open air do not suffer from this pent up accumu- 

 lation of heat, and are not excessively excited thereby, and, 

 when cool, cloudy weather follows a warm, bright season, 



* In 1836, when visiting the vineyards near the Rhine, and on the border of the 

 Lakes of Neufchatel and Geneva, I found the weather very cool, as compared with 

 the temperature of that season of the year in Massachusetts, the thermometer, during 

 August and September, var3'ing from 46°, the lowest point at night, to G0°, and, by 

 day. the highest point being 76° in the shade. Notwithstanding the low point at 

 which the mercury fell during the night, the grapes ripened finely. The vines here, 

 though subject to an intense heat when the sun shone upon the vineyards upon the 

 side of the hills, were, nevertheless, in an atmosphere which did not vary more than 

 10° or 15° in the daytime, excepting when the sun was shining upon them, and, being 

 in the open air, there was no confined heat there. 



