ON THE HEAT IN FORCING-HOUSES. 215 



and as experiments of this kind cannot bo made by the common gardener, 

 who must not risk the sacrifice of his employer's crops of fruit, I trust 

 the following account will be honoured by the approbation of the Horti- 

 cultural Society, though the experiments have been chiefly confined to 

 the peach-tree. 



As early in the spring as I wished the blossoms of my peach-trees to 

 unfold, my house was made warm during the middle of the day ; but 

 towards night it was suffered to cool, and the trees were then sprinkled, 

 by means of a large syringe, with clear water, as nearly at the tempera- 

 ture at which that usually rises from the ground, as I could obtain it ; 

 and little or no artificial heat was given during the night, unless there 

 appeared a prospect of frost. Under this mode of treatment the blos- 

 soms advanced with very great vigour, and as rapidly as I wished them, 

 and presented, when expanded, a larger size than 1 had ever before seen 

 of the same varieties : which circumstance is not unimportant, because 

 the size of the blossom, in any given variety, regulates, to a very consider- 

 able extent, the bulk of the future fruit. As soon as the blossoms were 

 expanded, and the pollen began to shed, water was applied in less 

 quantity, as a light shower, sufficient to wet the pollen, without washing 

 it off; but when the pollen was chiefly shed, I again, to promote its 

 absorption, sprinkled the trees abundantly with water, having previously 

 often observed that heavy showers of rain are at this period always 

 highly beneficial to the blossoms of the apple trees in our orchards ; and 

 almost every blossom of my peach-trees set most perfectly. The watering 

 was regularly continued till the fruit became very nearly ripe, the roots 

 of the trees being, at the same time, abundantly supplied with moisture 

 and food in the manner detailed in my last paper, in which I have stated 

 the more than ordinary size and perfection of the fruit. 



My house had been previously much infested with the red spider*; but 

 not a single one now appeared, nor scarcely an aphis ; and the young 

 wood became remarkable for the shortness of its joints, and the thickness, 

 comparatively with the length of its shoots. A gardener, who is preju- 

 diced in favour of old customs, will possibly imagine that he supplies the 

 place of the cool evening dews of nature, and of the water in the pre- 

 ceding experiment, by sprinkling his flues with water, and filling his 

 house abundantly with steam. But the effect of no two operations can 

 be more different : in the one, the plant is suddenly chilled by cold water, 



* I suspect, but I am no entomologist, that two distinct species of insect are confounded 

 under this name, one of which forms a web, which the other does not. The latter kind often 

 abounds in the open air, upon pear-trees, and appears to be, in the forcing-house, a much 

 hardier insect thrtn the other. 



