Transactions of the London Horticultural Society. 227 



obtaining bottom heat by means of " a cistern of water heated by small steam- 

 pipes, which are introduced near the bottom, leaving only sufficient drainage 

 to take away the condensed water. The depth of water in the cistern is about 

 1 ft. ; which is warmed, generally about twice a day, by means of two one-inch 

 steam-pipes, each going to the farther end of the cistern, and returning again 

 in the opposite direction, as shown in^g. 23.: by this means the heat is very 



easily distributed. At each end 

 of the cistern, a small passage 

 (a) is left, for the purpose of 

 ascertaining the temperature of 

 the water ; and this passage will, 

 if left open, admit considerable 

 humidity to the house or pit. 

 Across the cistern are laid joists, which support a paving of stone or brick, 

 laid without mortar, on which is placed a bed of broken stones or bricks^ 

 about 1 ft. in thickness, which, towards the top, are about the size commonly 

 used for macadamising the public roads : this is again covered with a bed of 

 ashes, in which the pots are placed, as in the usual way." 



For Bulbs and Cacti, " a 

 paved water-tight bottom may 

 be built on stones, or any suit- 

 able support, with a declivity of 

 1 in. in 10 ft., to any convenient 

 point for the purpose of drain- 

 age, as shown in Jigs. 25. and 

 26. Channels are formed about 

 3 in. deep, and the same width, 

 crossing each other, as shown 

 in fig. 26. ; which also repre- 

 sents two small steam-pipes, 

 each three quarters of an inch 

 in diameter, closed at the far- 

 ther end, and having perfor- 

 ations about one tenth of an 

 inch in diameter opposite each 

 other, and in the middle of the 

 channels. The result is, that, when steam is admitted into the pipes, it is 

 discharged in opposite directions, through the orifices, filling the whole space 

 of the channels with hot vapour j the channels being covered with brick or 

 stone, jointed without mortar, as shown in Jig. 26. The vapour which per- 

 colates between the joists is arrested by a bed of stones or broken bricks, 

 similar to those used in Jig. 24., and about 14 in. in depth above the paved bot- 

 tom : on this, again, is placed a bed of sand, about 1 ft. deep, in which the 

 pots are plunged to any suitable depth. The vapour is so completely arrested 

 by the strata of stones and sand beneath the pots, as to communicate a heat 

 congenial to the health of the plants, without the least excess of moisture." 



For Melon Pits, a hollow chamber is formed over the bed of stones that 

 cover the steam-pipes, as in the plan for pines. (Jigs. 23. and 24.) " Imme- 

 diately over the bed of stones are laid joists, supporting a paved bottom, 

 jointed without mortar, on which is placed another bed of stones, &c, about 

 8 in. thick ; and on this is placed the mould containing the plants. The 

 objects of these arrangements are, first, to obtain a perfect uniformity of tem- 

 perature ; and, secondly, to prevent the possibility of" any of the roots receiving 

 injury from heat, should they accidentally strike through the mould into the 

 bed of stones ; both of which objects are perfectly attained. Figs. 27. and 

 28. represent an elevation and plan of a melon pit erected for W.W. Salmon, 

 Esq., at Devizes, showing also the mode of heating the atmosphere of the 

 pit by flues of loose stones heated by steam-pipes. The arrangement of 

 these pipes, and the paved bottom channels for vapour, &c, are precisely the 



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