12 Progress of Horticulture 



heat being supplied by pipes in a chamber beneath, and is 

 warmed with one of Mr. Whately's cast-iron boilers. 



The principles of heating are now a subject of much discus- 

 sion m foreign journals. We alluded last year to the system 

 which was attracting so much interest, viz., the Polmaise. 

 Flues have had their day, — steam succeeded, — hot water took 

 its place, — and now comes the Air Ki?ig to dethrone them 

 all. According to the accounts which have been given, the 

 mode of heating by warm air has been far more successful 

 thus far, — as well as, it is stated, more congenial to the plants, 

 — and at not a quarter of the expense, — than hot water. Two 

 years ago we tried a small house heated upon this system, but 

 it did not succeed, owing to improper construction; this year 

 we have again partially tried this plan, and it appears to work 

 admirably. The Polmaise system is merely the construction 

 of a chamber over the furnace, from whence the air is con- 

 ducted into the house, and, traversing its length, when it 

 becomes cool, is brought back by drains under the floor, to be 

 heated again. Thus a constant circulation is going on, which 

 is highly congenial to the plants, moisture being supplied by 

 a pan of water, over which the hot air must pass as it comes 

 into the house. For the climate of England, there is no doubt 

 of its perfect success, but for our severe weather it remains to 

 be seen whether it can be made to answer ; the only requisite 

 will be a powerful furnace to supply hot air. We shall soon 

 give some plans and a further account of this new mode, 

 that our amateurs may be induced to try it; for vineries 

 where only a slight heat is required, in the months of March 

 and April, it will succeed well. 



COMMERCIAL GARDENING. 



The increase of nurseries is the best evidence of the prosper- 

 ous condition of Commercial Gardening : a large extent of 

 country to supply, with an increasing taste every where ap- 

 parent, has caused a demand which has not been fully met, 

 particularly in choice varieties of pears. In the Atlantic cit- 

 ies, this is especially the case. But large quantities of stocks 

 have been planted out, and we may soon look to a supply 

 fully adequate to the wants of the public. 



