The gardener's magazine and register of rural & domestic improvement (1826)
Loudon, J. C. (John Claudius), 1783-1843, A. & R. Spottiswoode, printer, United States. Patent Office. Scientific Library, former owner DSI · London : Longman, Rees, Orme, Brown and Green · leaf 193
5th, Where heat is required only during the action of the fire, alarge surface in proportion to its capacity may be used with advantage, togive off heat over the descending pipe (^figs. 26. and 27.): cooling iii thi^manner will increase the velocity. … 6th, The aperture of the upper pipe should not be more than about1 in. below the surface of the water, or as much as prevents its drawingail-, in an open boiler; but the lower it is below that, the less effect will be N 3 182 Transactions of the Horticultural Society. 27
