32 
MUSHROOMS, HOW TO GROW THEM. 
spacious stokehole. Here it is set under the stairway in 
a pit four and one-half feet long, by three feet wide, by 
eighteen inches deep; it is not in the way, and there is 
plenty of room to attend to it. The heater, like a corm 
men parlor stove, has a magazine for the supply of coaL 
Fig. 5. Base-burning Water 
Heater. 
Fig. 6. Vertical Section. 
It has a double casing with the water space between and 
down to the bottom of it, so that when set in a shallow 
pit there is no difficulty whatever about the circulation 
of the water in the pipes. The hot water passes from 
the boiler to an open iron tank placed two feet above it, 
as shown in the engraving, and thence down through a 
perpendicular pipe till it reaches and enters the hori¬ 
zontal pipes that pass around the cellar and, returning, 
enters the boiler again near its base. The boiler and 
pipes are filled from this tank, which should always be 
kept at least half full of water, and looked into every 
day when in use, so that when the water gets lower than 
half full it may be filled up again. About 134 running 
feet of four-inch pipe are included inside the cellar 
(sixty-four feet on each side and six feet across at further 
end); this gives 134 square feet of heating surface, or a 
