1826.] Mr. Daniell on Climate. 129 



suggestion, and it has been found that the plants have grown, 

 with unprecedented vigour : indeed their luxuriance must strike 

 the most superficial observer. 



To the human feelings the impression of an atmosphere so 

 saturated with moisture is very different from one heated to the 

 same degree without this precaution ; and any one coming out 

 of a house heated in the common way, into one well charged 

 with vapour, cannot fail to be struck with the difference. Those 

 who are used to hot chmates have declared that the feel and 

 smell of the latter exactly assimilate to those of the tropical 

 regions. 



But there is a danger attending the very success of this expe- 

 riment which cannot be too carefully guarded against. The 

 trial has been made in the summer months, when the tempera- 

 ture of the external air has not been low, nor the change from 

 day to night very great. In proportion to the luxuriance of the 

 vegetation will be the danger of any sudden check, and it is 

 much to be feared, that unless proper precautions are adopted, 

 the cold, long nights of winter may produce irreparable 

 mischief. 



I am aware that a great objection attaches to my plan of the 

 double glass, on account of the expense, but I think that this 

 may appear greater at first sight than it may afterwards be found 

 to be in practice. It is however, at all events, I submit, a point 

 worthy of the Horticultural Society to determine, and if the 

 suggestion should be found to be effective, the lights of many 

 frames which are not commonly in use in winter might, without 

 much trouble, be fitted to slide over the hot-houses during the 

 severe season : and in the spring, when they are wanted for 

 other purposes, their places might be supplied at night by mats 

 or canvass. 



The principles which I have been endeavouring to illustrate 

 should be doubtless extended to the pinery and the melon 

 frame, in the latter of which a saturated atmosphere might be 

 maintained by shallow pans of water. An increase in the size 

 of the fruit might be anticipated from this treatment, without 

 that loss of flavour which would attend the communication of 

 water to the roots of the plants. 



I have but few additional observations to oflfer upon the artifi- 

 cial climate of a green-rhouse. The remarks which have been 

 made upon the atmosphere of the hot-house are applicable to it ; 

 though not to the same extent. The plants which are subject 

 to this culture seldom require an artificial temperature greater 

 than 45° or 50°, and few of them would receive injury from a 

 temperature so low as 35°. Wlien in the house they are efi'ec- 

 tually sheltered from the effects of direct radiation, which can- 

 not take place through glass ; but the glass itseU radiates very 

 freely, and thus communicates a chill to the air, which might 



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