350 FORCING GARDEN. 



Mr. M'Murtrie, and it will be understood by the sect/on 

 and plan given in the preceding figures. 



A shallow bark-bed, about two feet deep, rests upon an 

 arched chamber of single brick. 1, is the fire-place; 2, a 

 fire-flue running along the whole length of the chamber 4, 

 which is also kept full of steam by means of the boiler and 

 pipe 3 ; the aperture 5, admits steam and heat into the air 

 of the pit, and of these there is one, both in back and front, 

 under each sash, capable of being stopped at pleasure. 

 The waste-pipe 6, allows the steam to escape, when the 

 apertures marked 5, are shut. By the return of the flue 

 2, the atmosphere of the house is heated ; and by the joint 

 action of the inclosed part of the flue, and of the steam in 

 the chamber, an abundant and salubrious bottom-heat is 

 easily maintained. 



The proper management of bottom-heat is a matter of 

 some difficulty, and in this there have been more failures 

 than in any other part of the pine-apple culture. The 

 heat arising from violent fermentation is greater than the 

 tender roofs can bear, and, if all watchfulness be not em- 

 ployed, the labor of many months may be blasted in a 

 single day. Mr. Knight discarded bottom-heat altogether ; 

 but he did not succeed in convincing others that pine- 

 apples could be grown equally well without it. Bottom- 

 heat is, however, very generally, kept too high. Perhaps 

 the upper limit of its temperature may be fixed at blood- 

 heat, or at most 100° , while the under or winter limit 

 may be brought down to 70 ° or 75 ° . Gardeners are 

 accustomed to judge of the heat of the bed by means of 

 long sticks pushed into it ; these are occasionally drawn 

 out and felt by the hand, and a rough guess at the tempera- 

 ture is thus obtained. A far preferable method is to em- 

 ploy a slow thermometer, slightly cased in wire, to protect 

 il when pushed into the bed. 



