ON THB CLIMATE OF HOTHOUSES. 275 



poses, their places might be supplied at night by mats or canvas. 

 The principles which I have been endeavonrmg 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 sue of the irmt 

 might be anticipated from this treatment, without that loss oi 

 flavour which would attend the communication of water to the 



roots of the plants. 



I have but few additional observations to offer upon the arti- 

 ficial climate of a green-house. 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 tempera- 

 ture so low as 35-. When in the house, they are eftectua ly 

 sheltered from the effects of direct radiation, which cannot take 

 place through glass; but the glass itself radiates very freely and 

 thus communicates a chill to the air, which might effectually -be 

 prevented by rolling mats. With this precaution, fire would be 

 but rarely wanted in a good situation to communicate warmth; 

 but in this damp climate it may be required to dissipate moist- 

 ure The state of the air should be as carefully watched with 

 this view, as where a high temperature is necessary to guard 

 against the contrary extreme. Free transpiration, as I have be- 

 fore remarked, is necessary to the healthy progress of vegetation; 

 and when any moodiness or damp appears upon the plants, the 

 temperature of the air should be moderately raised, and free ven- 

 tilation allowed. When the pots, in the proper season are 

 moved into the open air, it would contribute greatly to their 

 health, and preserve them from the effects of too great evapora- 

 tion, to imbed them well in moss or litter: as a substitute for 

 this precaution, the plants are generally exposed to a northern 

 or eastern aspect, where the influence of the sun but rarely 

 reaches them, but which would be very beneficial if their roots 

 were properly protected. The advantage of such a protection 

 may be seen when the pots are plunged into the soil a method 

 which communicates the greatest luxuriance to the plants, but 

 unfits them to resume their winter stations. 



When a green-house is made use of, as it often is after the re- 

 moval of the pots, to force the vine, the same precaution, should 

 be attended to as in the management of the hot-house, and the 



