530 



THE PRACTICAL GARDENER. 



edges ; tlicy possess the advantage over common bricks, in the 

 more rapid transmission of heat, and being easier heated ; but, 

 on the other hand, the refrigeration takes place as rapidly, for 

 want of sufficient body to retain the heat. 



An improvement upon these bricks has been invented, and 

 adopted by Mr. Mackay, of the Clapton Nurseries, in the ex- 

 tensive and convenient houses which have been built by him ; 

 the thickest part of the bricks used by him is less than that in 

 common use, and the middle of each is hollowed out to about 

 half their thickness ; they are very neat bricks, and no doubt 

 exists of their answering the purpose for which that intelligent 

 and industrious cultivator has designed them. They will evi- 

 dcnlly heat the atmosphere of the houses sooner, and with less 

 fire, which is extremely important to nurserymen; but they 

 will, of course, be cooled exactly in the same proportion, for 

 want of sufficient body to retain the heat. For green-houses 

 they are admirably suited, as slighter fires are necessary for 

 them, and their application generally requires to be more sud- 

 den to repel sudden attacks of frost ; but for the forcing of 

 fruits, where steady and uniform fires are required, we "\vould 

 prefer bricks of the usual form and size, which, although they 

 require a little more fuel to heat them, when once charged 

 with heat, they retain it equally long, and give it out gradually 

 for a greater length of time. Tiles, as broad as the tlue, or 

 nearly so, and a foot or fourteen inches long, should be used 

 for covers, and should be made hollow in the middle of their 

 upper surface, for the purpose of holding water for steaming 

 the house. 



Flues should be built clear of the ground, and detached 

 from the other walls, so that the heat may not be prevented 

 from escaping freely from their sides. The bottom of the flues 

 should stand clear of the floor of the house, the thickness of 

 one brick at least, if more, so much the better, but not so 

 as to raise the flue to an objectionable height. The sides 

 should be built of well-formed bricks, laid on edge, closely 

 jointed with washed lime, mixed with brick-dust, and should 

 not be plastered either outside or inside. If the bricks be well 

 laid, and neatly jointed, the flue will present a much neater 

 appearance than if plastered all over. The covers may be 



