230 HEATING AS APPLIED IN HORTICULTURE. 



rapidly. It is therefore by no means the 

 best mode of heating plant-houses where 

 a uniform or steady heat is required, un- 

 less it is made the medium of heating 

 other bodies, such as water or masses of 

 loose stones, either of which, when once 

 heated, gives out its heat regularly and 

 slowly. Mr Hay of Edinburgh employed 

 steam to heat masses of loose stones which 

 formed the bed on which the plants grew. 

 Roundish, hard, water-worn stones, or 

 broken granite, are preferred, as being 

 less liable to crumble away than soft 

 sand-stones. The steam -pipe is intro- 

 duced at one end of such a bed, near to 

 the bottom, and carried right through it. 

 It is finely perforated with holes along 

 both its sides for the free escape of the 

 steam amongst the stones. " The steam 

 only requires to be introduced once in 

 twenty-four hours in the most severe 

 weather; and in mild weather, once in 

 two or three days is found sufficient. 

 After the steam is turned on, it is kept 

 in that state till it has ceased to condense 

 among the stones, and consequently has 

 heated them to its own temperature. 

 This is known by the steam escaping 

 either through the soil over the stones, or 

 through the sides of the pit ; or where a 

 mass of stones is enclosed within a case 

 of masonry, as in the stone flues in the 

 Bristol nursery, the point of saturation is 

 known by the safety-valve of the boiler 

 being raised." — Encj/clopcedia of Garden- 

 ing, p. 593. Such being, therefore, the 

 case, might not the waste steam of manufac- 

 tories, or other works using steam-engines, 

 be brought to a useful purpose in the for- 

 cing of fruits or flowers for the proprietor's 

 own use, or even for supplying the public 

 markets? We recollect to have seen 

 steam employed to heat cisterns and pipes 

 of water some years ago in the Bristol 

 nurseries, and also to heat masses of 

 stones enclosed within walls of masonry. 

 The former of these plans had been even 

 before that period exemplified by Count 

 Zubow, at St Petersburg. Mr Stothert 

 of Bath carried heating by steam, by 

 heating cisterns of water, and also beds of 

 stones, to a very considerable extent. 

 Steam was applied in the garden of Mr 

 Sturge, near Bath, to heat the atmosphere 

 of a hothouse, making it the agent for 

 conveying the heat to pipes of water, and 

 carrying the small steam-pipes through 



the larger containing the water. " This 

 we think an excellent adaptation of steam, 

 and one which may be of advantage in 

 large places, 

 Fig. 310. more especial- 



ly when the 

 hothouses are 

 detached from 

 each other. 

 The follow- 

 ing figs., 310, 

 311, and 312, 

 and descrip- 

 from the 

 Encyclopse - 

 dia of Garden- 

 ing," p. 595, 

 will explain its 

 operation : — " The water-pipes are 8 inches 

 in diameter, and about 28 feet long," 



Fig. 311. 



tion 



Fig. 312. 



which we presume to be the length of 

 the house to be heated ; but if not, there 

 can be no reason why it should not. 

 " The steam-pipe, of 1 inch in diameter,- 

 entering at the centre of one end, and 

 proceeding in rather an inclined direction 

 to* the other, is then returned still inclin- 

 ing; and passed out at the bottom of the 

 bore immediately under the place where 

 it entered. It is then formed into a 

 siphon, b, about 3 feet deep, Whence the 

 condensed water is conveyed away. A 

 smaller pipe is also connected with the 

 top of the large one, to receive the in- 

 crease of water by expansion when heated, 

 which, as the large pipe cools, returns 

 into it again. Fig. 310 shows the ar- 

 rangement of the front pipe under the 

 floor. The air being admitted from the 

 air-chamber underneath, through an open- 

 ing extending the whole length of the 

 pipes, and passing through the upper 

 chamber on each side of the pipes, is 

 discharged through the grating into the 

 house. The arrangement of the back 



