4 



THE IKACIICAL (.AKULNER. 



pica! plants thaii is now used for the cultivation of pines, we then 

 found the pots plunged into beds of fermenting tanners' bark ; 

 but latterly, however, this method is almost abandoned, and 

 we find stove-plants now almost universally cultivated without 

 much bottom-heat, at least with no more than they receive 

 from the atmosphere of the house. A bed of prepared coal- 

 ashes, rendered perfectly porous beneath, to admit of all su- 

 perfluous water passing off, is now used, on which the plants 

 are set ; and it is only in particular cases that we now find 

 them plunged in a bottom-heat. 



Upon this subject, Mr. Sweet, a botanical cultivator of the 

 first eminence, offers the following remarks: — Some hot 

 dung or tan may be still kept in the pit to throw up a little 

 warmth, on which should be put a good thickness of sand or 

 gravel for the pots to stand on, and the plants will thrive much 

 better than if plunged in tan : it is also coming nearer to 

 nature, which should be always studied in the cultivation of 

 plants, both in soil and situation. In tropical countries it is 

 the sun that heats the earth in which the plants grow, not the 

 earth that heats the air ; and the heat must be kept up in the 

 stoves accordingly. If the house be heated by steam, no tan 

 is required. The plants may be set on stages, or any way 

 that is most convenient. Some of them may be planted out 

 in the house, where they will grow in great perfection, and 

 flower and ripen fruit; but if grown in large pots, they will 

 answer quite as well." 



In the construction of plant-stoves, it may be necessary to 

 notice, that fewer openings for the admission of air are required 

 than in any of the other plant-houses, for this reason, that the 

 degree of heat, which must be always kept up within the 

 enclosed atmosphere, is so much gTeater than that of the o])cn 

 air, that the difference of the specific gravity of the two fluids, 

 when permitted to mingle by opening two or three sashes, 

 produces a more active circulation, and sooner approaches to 

 an equilibrium of temperature ; and, however numerous the 

 openings in the roof or sides of such houses may be, they can 

 seldom be made use of without reducing the house to too low 

 a temperature ; and as the plants are for the most part kept in 

 pots, and many of them being of slow growth, they are not 



