202 



HEATING AS APPLIED IN HORTICULTURE. 



these partitions are apertures 12 inches 

 in width, 2 inches in depth, and 6 inches 

 apart, by means of which the heat and 

 steam from the hotter parts of the tank 

 can act regularly on the cooler — thus 

 equalising the temperature throughout 

 the whole of the superincumbent mate- 

 rials. In the chamber underneath the 

 tank are 4-inch cast-iron pipes, (g in sec- 

 tion,) in which hot water circulates for 

 heating the atmosphere of the pit ; and in 

 order that the water may circulate freely 

 in these pipes, the top of the boiler should 

 be placed on a level with them. These 

 pipes, as well as those that lead to the 

 tank, are furnished with valves of a sim- 

 ple construction, by which the flow of 

 water can be regulated as circumstances 

 may require." Mr Mitchell's " reason for 

 placing the pipes underneath the tank is, 

 first, because it saves room ; and, second, 

 because in this way the whole atmo- 

 sphere of the pit is kept in constant cir- 

 culation, whereby ventilation is in a great 

 measure superseded during the short days 

 of winter, when cold renders the admis- 

 sion of air hazardous." The beds are 

 prepared by laying 3 inches of drainage 

 over the tank covers at e e; and the trellis- 

 ing is made in convenient pieces, so that it 

 may be taken out or put in with perfect 

 ease. The hot-water pipes being placed 

 under the tanks admits of the whole 

 being wrought with one boiler, which 

 could not be done, unless the siphon 

 principle were adopted, were the pipes 

 brought up to the level of the top of the 

 bed. External air should be admitted 

 into the vault under the tanks, which 

 would increase the circulation, and drive 

 the heated air out of the vault by the 

 two openings between the tank and bed 

 and the side walls. This is altogether 

 a very excellent pit. 



Glendinning 's mode of tank-heating. — 

 Mr Glendinning has shown, in a series of 

 sensible papers on heating and ventila- 

 tion, (published in "Gardeners' Chroni- 

 cle,") a system of tank or gutter heating 

 for the borders of conservatories. There 

 is no doubt, as is remarked by this intel- 

 ligent gentleman, that one of the princi- 

 pal causes of failure in the cultivation of 

 tropical plants in conservatories has been 

 in maintaining a high atmospheric tem- 

 perature, while at the same time the roots 

 of the plants have been imprisoned in a 



soil many degrees colder than that of 

 their native country. 



We shall quote his own words, which 

 are as follows : — " The accompanying 

 woodcut, fig. 262, will show a mode of 



Fig. 262. 



heating the bed of soil in a conservatory 

 with the greatest ease, and with the most 

 complete success. The section of the 

 house shows a series of hot- water gutters, 

 as originally invented by Mr Corbett, 

 covered with common tiles, in such a 

 manner as will permit a portion of the 

 steam to escape amongst the mass of 

 loose stones which supports the soil des- 

 tined for the growth of the plants. The 

 stones themselves will constitute perfect 

 drainage to the conservatory bed ; at the 

 same time the moisture which ascends in 

 the shape of steam amongst the stones, 

 and that also which filtrates through the 

 earth in which the plants are growing, 

 will readily escape, and cannot in either 

 case injuriously influence the health of 

 the plants ; but the very contrary will be 

 the result, as when the heat in the gut- 

 ters is increased under such circumstances, 

 so also will be the moisture — thus secur- 

 ing the soil from becoming exhausted or 

 desiccated by the constant application of 

 heat to the roots, which is the defect in 

 all common contrivances of this kind that 

 supply bottom heat." 



Fleming's mode of tank-heating. — The an- 

 nexed figs., 263 and 264, represent a 

 pine-pit invented by Mr Fleming, the 

 intelligent superintendent of the Trent- 

 ham Gardens. We had the satisfaction 

 of seeing this pit shortly after its erec- 



