20 Management of Temperature hi Hot-houses. 



late vinery, which had received little assistance from fire heat 

 except at the blossoming season. During this season (1833), 

 the pine stove referred to, as well as all the other houses, were 

 managed upon a natural system. The temperature at night in 

 the pine stoves was frequently below 60°, and in the vineries as 

 low as 50°, while during the day the temperature ranged from 

 80° to 110°, the atmosphere being kept in a moderately humid 

 state. The grapes in the pine stove formerly noticed were ripe 

 from three weeks to a month sooner than last season ; the fruit 

 was of the finest quality, both as respects colour and flavour, and 

 so free from shriveling, that a number of bunches that were left 

 upon a white muscat vine with very large berries were cut, in 

 the end of last month, without containing one shriveling berry. 



Several gardeners with whom I have conversed upon the 

 subject, while allowing that the present general practice is un- 

 natural, at the same time contend that, when fruit is wanted 

 early, it is necessary to keep up a high temperature both night 

 and day; but the instance I have referred to tends to show that 

 such a practice, instead of accelerating maturation, actually 

 retards it, or, at any rate, leaves very little chance of obtaining 

 fruit of the best quality. As an additional fact, I might refer to 

 our field crops, which ripen most rapidly when exposed alter- 

 nately to the cold dewy nights and bright warm sunny days of 

 autumn. By allowing the temperature to fall at night, and to 

 rise by sunshine during the day, much less air will be necessary 

 than is generally given, and almost universally recommended, and 

 much labour will be saved. Indispensable as atmospheric air is 

 to plants, it appears to me that its importance has been greatly 

 overrated. However necessary its free admission is, to counter- 

 act the prejudicial effects of keeping a high temperature at 

 night, it is not in like manner necessary when the plants are 

 cultivated in accordance with the dictates of nature ; as the ex- 

 panding influence of a high temperature, from sunshine, will, at 

 the same time, be counteracted by the agerjcy of light effecting 

 the elaborating and decomposing processes. Its free admission, 

 for the purpose of imparting colour and flavour to fruit, may be 

 very proper when the fruit has attained its full size, and the 

 temperature is not much reduced; but it is worth enquiring 

 if, even here, light be not the principal agent. The very argu- 

 ment made use of by many, that it is necessary to admit a free 

 current of air, for the purpose of keeping the atmosphere pure 

 in which the plants are grown, will, when duly weighed, recoil 

 upon themselves ; as it is only at night that plants can deteriorate 

 the atmosphere, while they perform a salutary process of 

 purification during the day : to act consistently, it is during the 

 night that gardeners ought to give the greatest quantity of air. 

 I know that even this practice is recommended by some, but it 



