2129. For melon pits, a hollow chamber is formed over the bed of stones that cover the steam-pipes, as in the plan for pines, ﾺ 2127. 'Immediately 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 temperature, 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. 622. and 623. 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 same as above described; but in lieu of the bed of broken stones, &c., bricks are here placed edgewise, one over the other, four deep, arranged in the same manner as for burning in a kiln; over these bricks is laid a flat cover jointed close without mortar, and on this the mould containing the plants.'
