314 FORCING GARDEN. 



valves is sometimes employed. This mode of circulation 

 has been adopted in some of the principal nursery gardens 

 near London. 



Mr. Charles H. J. Smith, garden architect, in a com- 

 munication to the Scottish Horticultural Society, ha3 

 clearly shown that the system of heating by the circula- 

 tion of hot-water in metallic pipes is easily applicable, not 

 only to any glazed house constructed with flues, but to 

 any select portion of an existing fruit-wall, although al- 

 ready clothed with peach, vine, or fig-trees. In the last 

 case, a small furnace and boiler are, of course, placed at 

 the back of the wall ; the expanding water rises to a cis- 

 tern near the top of the wall; horizontal pipes, making 

 three or four turns, are inserted into the south front of the 

 wall (which is an easy operation, as the wall is usually 

 faced with brick) ; and through these the water circulates, 

 to the great increase of the temperature of the air sur- 

 rounding the tree. The operation should be accomplished 

 late in the autumn; the tree being carefully unnailed, bent 

 forward, and secured from injury or breaking, and as care- 

 fully replaced. 



Mr. A. Perkins has constructed an apparatus of small 

 tubes hermetically sealed, in which water circulates, of a 

 temperature varying from 300° to 400° Fahrenheit. The 

 contrivance is very ingenious, and has been pretty exten- 

 sively employed at London and Edinburgh, in heating 

 public oflices and warerooms ; but as the opinions of hor- 

 ticulturists respecting its merits, as applicable to the forc- 

 ing garden, are still divided, and as it has not as yet stood 

 the test of much experience, it may be sufficient to give it 

 this cursory notice. For further information, however, 

 we may refer to the Gardener s Magazine, vols. viii. 

 and ix. 



