THE CULTURE OF THE GRAPE. 61 



morning in order to raise the mercurj in the thermometer to 

 about 70° during the day, and allow the fire to burn out 

 towards night. The temperature in the daytime, from the 

 commencement of forcing, should be regulated, in some 

 measure, by the heat of the vinehouse during the night. 

 For example, if the house has been colder during the night 

 than I could wish, I keep up a greater heat than usual during 

 the following day ; and, if it has been warmer during the 

 night than I consider requisite, I give less fire during the 

 day than usual ; or more air, according to the state of the 

 weather. 



" Many may object to the lowness of the temperature that 

 I have recommended during the night, when the grapes are 

 in flower ; but all the kinds cultivated here, including the 

 Tokay, Black Hamburgh, White Sweetwater, &c., uniformly 

 set well with the heat above mentioned. Indeed, Avhen the 

 nights have been frosty, during the time my vines were in 

 flower, I have seen the thermometer as low as 52° in the 

 morning, and I never observed that they sustained the least 

 injury by this low temperature. Too much dependence has 

 hitherto been placed on the influence of fire heat in the forc- 

 ino' of hothouses. The o;reat art is to do with as little fire 

 heat as possible, and to take the utmost advantage of the heat 

 derivable from the sun's rays, consistent with giving a suf- 

 ficient quantity of air. The legitimate use of fire heat is to 

 prevent the bad efiects of frosts, snows, and inclement weather. 



" I may now say a few words on giving air. In clear 

 weather it should always be given early in the morning, and 

 taken away early in the afternoon. For example, let a small 

 portion of air be given between eight and nine o'clock in the 

 morning, and, if the day continue clear, give more between 

 ten and eleven, and take it all away at three o'clock. I sel- 

 dom let air into my vinehouses after three o'clock in the 

 afternoon. If air be admitted until the house is completely 

 cooled, a large fire may be necessary to support the requisite 

 temperature ; and it is evident that sun heat is better and 

 cheaper than fire heat." — Sept., 1838. 



