GROWING MUSHROOMS IX CELLARS. 33 



proportion of about a square foot of heating surface for 

 every fifteen cubic feet of air space in the cellar. This 

 proportion is more than ample in the coldest weather, but 

 beneficial in so far that there is no need to fire hard to 

 maintain the proper temperature. A three-inch pipe 

 would have given heat enough, but the heat would not 

 have been so steady. Both nut and stove coal is used in 

 this heater, and in the severest winter weather it bums 

 not more than a common hodf ul in twenty-four hours. 

 It is so easily regulated that the temperature of the cel- 

 lar day or night, or in mild or severe weather, never 

 varies more than three degrees, namely from 57° to 60°. 

 In a close underground cellar where the temperature 

 in midwinter without any artificial heat does not fall 

 below 40° or 45° it is an easy matter, with such a heater 

 as this is, to maintain any desired temperature. If the 

 grates are renewed now and then, the heater should last 

 in good condition for twenty years. With the ordinary 

 stove there is danger of fire, of escaping gas and of sud- 

 den changes of temperature, and the evil influence of a 

 dry, parching heat — ^just wliat mushrooms most dislike 

 — is ever present. The first cost of a hot water appa- 

 ratus may be more than that of an old stove and sheet 

 iron pipes, but where mushrooms are grown extensively, 

 as a matter of economy, eflSciency, and convenience, the 

 advantages are altogether on the side of the hot water 

 apparatus. Furthermore, hot water pipes can be run 

 where it would be unsafe to put smoke pipes. 



