280 THE FORCING GARDEN, 



convince the operative gardener, contrary to the 

 evidence of his own senses, and his experience ? 

 Does he not well know, that the flue being thus 

 charged, will, and does cool again in a few hours ; 

 and requires of him the trouble of charging it again 

 and again ? Whereas, from a fire producing a slow 

 and constant stream of hot air, by which the flues 

 are kept in an equal state for the length of a win- 

 ter's night, his mind is at ease, and his body finds 

 rest. 



The furnace I use is calculated to produce this 

 effect ; and, I believe, has given very general sa- 

 tisfaction to operative men ; \yhich certainly is the 

 best test by which it can be tried. It is simply an 

 oven, capable of containing less or more fuel, ac- 

 cording to the kind of hot-house to which it may 

 be attached, and the kind of fuel to be used ; with 

 a grate in front just large enough to kindle the 

 mass of fuel, and keep it alive. I shall set down 

 the dimensions of one of a middle size. 



The oven is thirty inches long, and twenty inches 

 wide. The grate eighteen inches long, and ten 

 broad. The furnace-door ten inches square, with a 

 circular valve in the centre of it, three inches in 

 diameter. The ash-pit door is of the same con- 

 straction and width, but fifteen inches deep. These 

 valves turn with a handle, and are capable of ad- 

 mitting any quantity of air, to the extent of half 

 their diameters, which is deemed sufficient. The 

 sole of the oven is placed twelve inches below the 

 level of that of the flue, and is paved with fire- 

 brick.. The walls are also formed of fire-brick, to 



