THE EARLY GRAPERY OR FORCING HOUSE. 85 



stream of cold air to pass over and among the leaves, as 

 it traverses upwards, and forces the heat out ; most of the 

 mildew that attacks roses and verbenas in the winter time 

 is produced by this cause, and if such plants as these suffer, 

 surely the grape vine must share the same fate. One of 

 the worst things that we have to deal with in forcing this 

 fruit is the extreme difference of the outside temperature 

 from that which is essential for its well-doing inside of the 

 house ; and particularly during its more easily injured 

 stages, there are the most frigid blasts to contend against, 

 and very sudden transitions, from dull or cloudy weather, 

 to bright sunshine ; owing to which it behooves us to study 

 carefully how we proceed, and imitate as nearly as we can 

 those peculiarities of natural climate which observation 

 shows to be. conducive to the most healthy development. 

 This is more particularly mentioned here, because many 

 persons are prone to take advantage of all the little oppor- 

 tunities that occur to admit "fresh air," without taking into 

 consideration these principles in trying to accomplish the 

 object in view. 



So soon as the buds are well burst, the vines may be 

 tied to the wires in their permanent position, and the heat 

 very slowly but gradually increased ; if it were possible 

 to be so exact, about two thirds of a degree per night and 

 one each day in clear weather would be about an average, 

 until 65 at night, and 80 to 90 by day (according as it 

 might be cloudy or sunshine) were arrived at. As the 

 shoots continue to elongate, tie them to the side wires, but 

 be careful not to commence this operation too soon, as they 

 are very brittle, and subject to break off at the axil when 

 young. The bunches by this time will be readily seen and 

 as the future treatment with regard to fertilization, stop- 

 ping, thinning, &c., is the same as explained in the last 

 chapter, there is no occasion for repetition. The greatest 



