HEATING THE RANGE 109 



strands of tarred rope for a foundation. On top of this 

 foundation iron borings moistened with water are caulked. 

 This joint when tightly and properly caulked is one of 

 the best joints possible, for it is then of the same sub- 

 stance and same consistency as the pipe itself, and is, 

 therefore, subject to the same degree of expansion and 

 contraction. 



" The great advantage of using large pipes has been 

 explained, i.e. that they carry their heat better through 

 the night than do smaller pipes. There is another and 

 quite as important a quality, which is that cast-iron 

 pipe will often last twice as long as wrought pipe. There 

 are many systems still in use which were constructed of 

 cast-iron pipe thirty-five or forty years ago. 



" The small pipe referred to is 2-inch wrought-iron 

 pipe, which is used now more extensively in commercial 

 plants than in private systems. The reason for this is, 

 doubtless, that wrought-iron pipe is cheaper per linear 

 foot and cheaper per square foot of surface than cast-iron 

 pipe, and also because the commercial grower is willing 

 to give some attention to his heating system if necessary, 

 through the night, if his plant is small ; and if his plant 

 is large, he keeps a night fireman, so the carrying power 

 of the larger pipes is not expected and is not so necessary. 



" The coils of 2-inch pipe are constructed in the same 

 manner as those of 3|-inch pipe and are placed in the 

 same way under the benches, only it is necessary to place 

 more lines of 2-inch pipe than would be necessary of 

 3J-inch pipe; 1.68 linear foot of 2-inch pipe is equivalent 

 to 1 linear foot of 3J-inch pipe in superficial surface, and 

 contains a little more than one-half the quantity of water 

 contained in one linear foot of 3|-inch pipe. Two-inch 

 pipe fittings and automatic air headers are now made 



