274 ON THS CLIM1TK OF HOTHOUSES. 



proportioned in a very high degree to its motion. I would sug- 

 gest, as a matter of easy experiment, whether great benefit might 

 not arise from warming the air to a certain extent, and making 

 it traverse a wet surface before it is allowed to enter the house. 



There is one practice universally adopted by gardeners, which 

 is confirmatory of these theoretical speculations ; namely, that of 

 planting tender cuttings of plants in a hot bed, and covering them 

 with a double glass. Experience has shown them that many 

 kinds will not succeed under any other treatment. The end of 

 this, is obviously to preserve a saturated atmosphere ; and it af- 

 fords a parallel case to that of Dr. Wells, of the anticipation of 

 theory by practice. 



The effect of keeping the floor of the hot-house continually wet, 

 has been already tried at the Society's garden, at my suggestion, 

 and it has been found that the plants have grown with unpre- 

 cedented vigour ; indeed their luxuriance must strike the most 

 superficial observer. 



To the human feelings, the impression of an atmosphere so sa- 

 turated 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 climates, 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 temperature of 

 the external air has not been low, nor the change from day to 

 night very great. In proportion to the luxuriance of the vege- 

 tation, 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 sug- 

 gestion 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 pur- 



