250 
ON THE CONSTRUCTION AND HEATING OF HOT-HOUSES. 
charcoal and cinders, the inconvenience of smoke would be avoided, and sufficient 
draught obtained by a moderate length of stove pipe passing through the roof* 
This plan was adopted, and answered completely. 
Fig. 1. ' * " 
Fin. 2. 
Fig. 1 is a vertical longitudinal section : A, B, C, D, the outer cylinder or 
boiler, three feet long and one foot in diameter ; E the fire-place ; F the door, lined 
with a mixture of fire clay and pumice-stone ; G the ash-pit, furnished with a drawer 
of sheet iron. 
The fire-place and ash-pit are contained in the inner cylinder, which is half the 
length of the boiler, and nine inches in diameter. From the back of the fire-place, 
an elliptical flue, H, proceeds nearly to the end of the boiler, then returns again 
towards the front, and passes out at I into the chimney K. L is a cylinder for sup- 
plying the boiler with water, and allowing for its expansion when heated : M M, 
the water-pipes, (shown in section fig. 2,) connected with the boiler by screws or 
flanges at O O. These pipes are elliptical, which shape combines in some measure 
the strength of the circular with the extended surface of the flat form. The pipes 
are only twelve feet long ; but the circulation is so rapid that the boiler would serve 
for a much greater length ; N is an air-pipe. 
Fig. 1. 
This small apparatus has answered so well, and appears to offer so many advan- 
tages over a boiler set in brick-work, that the writer has been led to consider how 
the plan may be improved upon, and applied to heating houses of large dimensions 
with any sort of fuel. This might probably be accomplished by constructing the 
apparatus according to one or other of the plans of numbers 3 and 4, where the 
