PIPES FOR IRRIGATION PURPOSES. 91 



Iii laying the pipe the trench is usually excavated at 

 least eighteen inches wider than the outer diameter of 

 the pipe, to provide standing room for the workmen ; the 

 number of staves needed to form the pipe are placed in 

 piles along the trench and a foreman with five workmen 

 form a gang. The tools used by a gang are a twelve- 

 pound sledge, an oak driver banded on one end, four 

 two-pound hammers, two chisels, four crank wrenches, 

 two inside forms of coiled gas pipe and two outside U- 

 >shaped forms of the same material. A completed line 

 of stave pipe with an abandoned flume just above it is 

 pictured in Figure 27. In this instance the pipe was 

 kid above ground, as can just as well be done in coun- 

 tries where the winters are mild. The capacity of a 

 thirty-inch skive pipe is computed on thirty inches 

 diameter as follows : 



Cost of Pipes. To determine the capacity of any 

 pipe it may be well to remember that twice the given 

 diameter increases the capacity four times. The factor 

 of first cost to the pipe, while it is undoubtedly the one 

 requiring the least labor to determine, is also the most 

 difficult to arrive at with exactness. Being subject to 

 commercial laws cf supply and demand, transportation, 

 competition, etc., this item is so variable that exact esti- 

 mates can only be given for the present, which may not 

 be at all reliable for the future. It will therefore be our 

 aim to present estimates of cost which may be taken as 

 a fair average and will be relatively correct as between 

 the different kinds of pipe. With this in view the fol- 



