792 On the Use of Steam Heat. 



tion. It is necessary, however, to take care that the 

 boiler be placed lower than the stove, in order that 

 the water resulting from the condensation of steam in 

 the stove may return to the boiler. 



4th. Since the boiler will be provided with safety- 

 valves, the stove will never be in danger either of being 

 burst by the elastic force of the steam, or of being 

 crushed by the pressure of the atmosphere ; and on 

 this account it may be constructed without difficulty of 

 very thin sheets of copper, so that the expense of its 

 construction ought not to be very great. 



5th. These stoves may be made of any desired form; 

 but the best shape is that of a cylindrical tube, or of 

 a column, for this is the form which gives them the 

 greatest strength to resist, without change of shape, 

 the expansive force of the steam within and the pres- 

 sure of the atmosphere on the outside. 



6th. The steam should be introduced into the stove 

 at its upper extremity; and in the lowest part of the 

 stove there should be a tube to conduct into the boiler 

 the water which results from the condensation of steam 

 in the stove. In order that the tube which conducts 

 the steam into the stove may not be visible in the 

 apartment, it may be made to enter through the bottom 

 of the stove, and then ascend inside, to within 2 or 3 

 inches of the upper end, where there should be an 

 opening. As the vapour of boiling water is specifically 

 lighter than atmospheric air, by bringing the steam into 

 the upper part of the stove it presses upon the air in 

 the stove, and drives it out by one of the safety-valves 

 without mixing with it, so that this air is driven out 

 quietly, and without first being warmed at the expense 

 of the heat of the apparatus. This air must descend 



