150 Polmaise Method of Heating Hothouses. 



his pen and influence, he never had one erected at the Hor- 

 ticultural Societies' garden, where he had unlimited control ; 

 Something of the kind, I believe was tried in a small pit, but 

 the results were not given to the public, and those who 

 erected them by his recommendation, were obliged to ac- 

 knowledge them unqualified failures. 



Polmaise has been improved and modified in many ways 

 since its introduction under that name. It will be seen that 

 the only difference between it and the ordinary hot air stoves, 

 consists in the air being supplied from the interior of the 

 house, while in the stoves generally used, the air to be heated, 

 is drawn from the external atmosphere. Now, the air, pass- 

 ing over a highly heated surface and entering a house, of any 

 kind, at a high temperature, is bad enough, but the same vol- 

 ume of air, heated over and over again, is a hundred times 

 worse, so that the supposed advantage of Polmaise, is in re- 

 ality a defect, and one too, of sufficient importance to con- 

 demn its adoption ; for no water-tank contrivance has yet had 

 the effect of restoring the air thus heated, to its original purity 

 and healthfulness. And hence, the more recent modifiers of 

 Polmaise, have thrown this advantage aside and reverted to 

 the common method of hot air healing, which, applied to 

 hothouses, is quite as expensive as smoke flues in the be- 

 ginning, and triply expensive in the end, besides being far 

 more troublesome to work. The late Mr. Meek, of Holms- 

 dale, — who, upon the death of Mr. Murray, of Polmaise, 

 took up his mantle and a double portion of his spirit, — con- 

 trived a modification of the system, perhaps more scientific 

 and perfect in its arrangements than any of the others, but 

 not so simple as some of them. For instance, Lewis or Ken- 

 dall's, a plan of which is given in Allen's Treatise on the 

 Vine. And most assuredly, a more bungling aflfair for heating 

 a hothouse, — and one displaying more ignorance of the prin- 

 ciples by which air is heated and diffused — never was erected. 

 When applied in conjunction with an apparatus already heat- 

 ing a house, it may prove of some considerable service ; in 

 fact, the conduction of all the heat generated by the com- 

 bustion of fuel into the house, without loss or detention, is 



