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house was generally raised in hot and bright days, 

 chiefly by confined solar heat, from 95 to 105 degs., 

 and sometimes to 110 degs., no air being ever given 

 till the temperature of the house exceeded 95 degs. ; 

 and the escape of heated air was then, only in a slight 

 degree, permitted. In the night the temperature of 

 the house generally sank to 70 degs., or somewhat 

 lower. At this period, and through the months of 

 July and August, a sufficient quantity of pigeon's 

 dung was steeped in the water, which was given to 

 the pine-plants, to raise its colour nearly to that of 



time ; but depend on it, it will be found still a great advantage, 

 in pot culture, to have the plants standing partly plunged on 

 the platform in open porous sweet materials ; and nothing 

 would be so valuable for this purpose as charred refuse, which, 

 by a proper application of moisture, would always give off, in 

 the healthiest form, humidity, charged with ammonia ; and the 

 tank, gutter, or hot-pipe system of applying bottom heat could 

 be managed similarly, with the same materials as previously re- 

 commended, and a perforated pipe for furnishing the requisite 

 kindly humidity and warmth about their roots. We cannot 

 see how Mr. Knight could obtain the circumstances afforded by 

 nature, when his plants were placed on brick piers, and he ad- 

 mitted to them but little air, in an artificial structure, without 

 any material applied to absorb the natural heat, and give it off 

 charged with humidity, &c. This, however, would be accom- 

 plished by furnishing between the piers, or, which would be 

 better, amongst the pots, a body of charred materials. It is 

 astonishing how quickly, and to what extent, charcoal does ab- 

 sorb heat, retaining and giving it off in a genial manner. 



