312 



THE GARDENER'S ASSISTANT. 



can be moved according as the requirements of 

 the permanent trees demand it, and when the 

 time comes that they can be altogether dis- 

 pensed with, they are available for use else- 

 where. 



There are few things grown under glass, 



either flowering or fruit-bearing, that are more 

 benefited by bottom -heat than Oranges, for 

 although they can be grown without it, yet 

 they will not make so much progress in a given 

 time. In the case of trees that are to be planted 

 out in the manner described, and where it is 



Fig. 1094.— Orange Tree against a wall in the open air at Osborne. 



the intention to apply bottom-heat, this can be 

 done by constructing under each bed a chamber, 

 which it will be necessary to sink below the 

 level of the floor inside the house. Wherever 

 chambers of this description are used in which 

 to lay pipes for bottom-heat, they should always 

 be made large enough to admit of the pipes 

 being got at in case of leakage. Want of fore- 

 thought in this matter is often most serious in 



its consequences, the roots of trees grown over 

 the chambers having to be disturbed, or the 

 trees removed altogether, in order to repair 

 leakage. A flow and return pipe should run 

 in each chamber, with in all cases a valve to 

 regulate or entirely shut off the heat. There 

 is another matter that must never be lost sight 

 of when this or any other fruit is afforded bottom- 

 heat; that is, the liability of the soil at the 



