366 FORCING GARDEN. 



two fires each, it would b« better to have four pits with 

 single fires. There might be two succession-pits of the 

 forms represented, sup^a^ pages 362, 363, and two fruit- 

 ing-pits similar to the figures on page 364. These 

 would contain a much greater number of plants than 

 two pine-stoves, would be little more expensive in erec- 

 tion, and, as the number of fires is the same, would not 

 consume much more fuel. 



Bottom-Heat. — As a substitute for the warmth ab- 

 sorbed by the earth from the powoi^ful rays of the sun 

 in tropical countries, the pots of pine-plants are gene- 

 rally plunged in a bed composed of tanners' bark, de- 

 caying leaves, or other fermenting substances. Tan- 

 ners' bark is most commonly used. Speechly and 

 Nicol prefer leaves shed by hardwo-od trees in autumn. 

 Others form the under' and greater part of the bed with 

 stable-litter. Whatever substance is employed, it should 

 not be put into the bed until the first violent heat of 

 fermentation havje passed; or, if circumstances impose 

 a necessity of using it in a recent state, it should be 

 largely mixed with old materials of the same kind. A 

 layer of exhausted bark, ten or twelve inches thick, 

 should 'be laid on the surface of the bed. In pine- 

 stoves, the curb of the bark-pit is usually elevated 

 about three feet above the common level of the house, 

 and has a gentle slope towards the front ; in pine-pits, 

 however, it approaches more cl-osely to the. glass. The 

 bark is commonly five or six feet deep ; but it may be 

 questioned whether this depth is not excessive and un- 

 necessary. A bed about three and a half feet deep 

 would probably be more convenient, and afford a heat 

 sufiicient both in intensity and duration for any useful 

 purpose. 



