Heating by Steam. 41 



point. If on level ground, let your pit be deep enough 

 so the top of the boiler will be two or three feet lower 

 than are your returns at any point where they leave 

 your houses and are connected with a main ready to 

 be dropped perpendicularly or otherwise, and be con- 

 nected with the boiler at its lowest point. This will 

 give a fall of from six to ten feet according to the size 

 and kind of boiler you use, and is essential to a perfect 

 circulation. 



Third, see that your main pipe from which all the 

 lesser mains are fed, is of sufficient size. A boiler of 

 sufficient capacity to feed 10,000 feet of IJ inch pipe 

 should have a six-inch distributing main 15 feet long, 

 when it may be reduced to 4 inches, and this should 

 extend as far as the combined width of your houses, 

 whether you feed them all from one end, or whether 

 the distribution is made each way from a central house. 

 The size of the connecting-mains will depend upon the 

 length and size of the house. Two inches is sufficient 

 to feed six two-inch returns, or nine one and one-quarter 

 inch. If radiation is not wanted from this pipe it, as 

 well as the six-inch, should be well protected by. some 

 of the best forms of covering. The main which feeds 

 the house should be carried to its extreme end and 

 from that point distributed into as many returns as 

 are necessary to keep the temperature at the degree 

 desired. For a house eighteen feet wide one two- 

 inch flow and six two-inch returns, or one two-inch 



