IIQ FORCING HOUSE FOR GRAPES. 



by the gardener, when his prejudices satisfy him, that his 

 labours cunnot be successful. It is, however, sufficiently 

 evident, that, when the same fruit is to be ripened in the 

 same climate and season of the year, one peculiar form must 

 be superior to every other, and that in our climate, where 

 sunshine and natural heat do not abound, that form, which 

 admits the greatest quantity of light through the least 

 breadth of glass, and which affords the greatest regular heat 

 with the least expenditure of fuel, must generally be the 

 best : and if the truth of this position be admitted, it will be 

 very easy to prove, that few of our forcing houses are at pre- 

 sent ever moderately well constructed. I therefore think, 

 , that, if plans and descriptions of such forcing houses, as 

 theory and practice combine to prove to have been properly 

 constructed for the culture of every different species of 

 fruit, were published by the Horticultural Society, much 

 useful information might be conveyed to the practical gar- 

 dener: and under these impressions T send the following 

 description of a vinery, in which the most abundant crop* 

 of grapes have been perfectly ripened within less time, and 

 with less expenditure of fuel, than I have witnessed in any 

 other instance. 

 Best indina- It is well known that the sun operates most powerfully 

 in the forcing house, when its rays fall most perpendicularly 

 on the root : because the quantity of light, that glances off 

 without entering the house, is inversely proportionate to the 

 degree of obliquity, with which it strikes upon tb« surface 

 of the glasrs; and it is therefore important to every builder 

 of a forcing house to know by what elevation of the roof, 

 the greatest quantity of light can be made to pass through 

 it. To ascertain this point, i have made many experiments, 

 and the result of them has satisfied me that, in latitude 52, 

 the best elevation is about that of 34 degrees : and relative 

 to that elevation the position of the sun, in different part« 

 of the year, will be nearly as represented i n the annexed sketch, 

 pi. IV, fig. 4, which is taken from the vinery I have mentioned. 

 About the middle of May, the elevation of the sun will 

 nearly correspond with that of the asterisk A, and in the be- 

 ginning of June, and again early in July, it will be vertical 

 at B, and at Midsummer it will at C be orjly six degrees 



from 



tion of the 

 glass. 



