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XXXIII. On the ill Effects of excessive Heat in Forcing- 

 houses during the Night. By Thomas Andrew Knight, 

 Esq. F. R. S. $c. President. 



Read June 17, 1814. 



Few gardeners, if any, have ever believed plants to be at 

 all endued with powers of sensation and perception similar 

 to those of animals, or to be, in any degree, susceptible of plea- 

 sure or pain ; and yet it is very questionable, whether there 

 has ever been a single gardener, who, in the management of 

 fruit-trees in a forcing-house, did not in some respects err, 

 by treating his trees, as he would have done, if he had 

 supposed them to possess such powers. Being fully sensible 

 of the comforts of a warm bed in a cold night, and of fresh 

 air in a hot day, the gardener generally treats his plants, as 

 he would wish to be treated himself; and, consequently, 

 though the aggregate temperature of his house be nearly 

 what it ought to be, its temperature during the night, rela- 

 tively to that of the day, is almost always much too high. 

 The consequences of this excess of heat during the night are, 

 I have reason to believe, in all cases highly injurious to the 

 fruit-trees of temperate climates, and not at all beneficial to 

 those of tropical climates ; for the temperature of these is, 

 in many instances, low during the night. In Jamaica, and 

 other mountainous islands of the West Indies, the air upon 

 the mountains becomes, soon after sun-set, chilled and con- 

 densed, and in consequence of its superior gravity, descends 

 and displaces the warm air of the vallies ; yet the sugar 



