ON WARMING HOTHOUSES. BY STEAM. 
Several valued friends having expressed 
a desire of information respecting the mode we are 
practising of Heating our Houses by Steam, we have 
been induced to draw up the following short account 
of the apparatus as it stands at present in full work. 
It will be needful to begin at the Boilers, as being 
the source of action. . We have two, although one only 
is needed, or can be used at one time; but in ease of 
repairs being wanting, the other is always in reserve, 
to prevent any interruption of heat. They are both 
of equal size, 11 feet long, 43 wide, and 54 deep, of 
wrought Iron, fitted up precisely as common Steam 
Engine Boilers (cc, Plate 1). A Cistern above (d) 
supplies them with water in the usual way, by a self- 
feeding apparatus, composed of a feed head (e) in 
which is a valve, which is opened by the descent of a 
stone float in the boiler as fast as the water evaporates, 
and being balanced by ‘a weight, the moment the 
water is replenished the float rises and shuts the valve. 
To guard against any danger which might arise 
from the too great force of the Steam, a Safety Valve 
(Y is affixed: this is loaded so as to rise whenever 
the steam i is of a greater pressure than Alb. upon the 
square inch : it immediately eseapes through the pipe 
to the-outside of the building. 
There is also another valve (% to admit atmos- 
pheric air whenever the condensation of steam causes 
a vacuum in the boiler. 
2 MEEL är Dl ts Å 
