30 



As regards the cost of installation the first type ha the advantage that 

 the cost per acre of the distribution system is less than that of a wooden 

 pipe system. For ordinary conditions it is roughly estimated that a 

 wooden flume system will cost one-half as much as a wooden pipe system. 

 For very rough land requiring a great deal of fluming on high trestles, the 

 comparison in cost would not be so favorable to wooden flume. As far as 

 durability is concerned, the life of a well constructed wooden flume should 

 be between 8 and 12 years. The life of a wooden pipe which is full only 

 part of the time is problematical; it depends somewhat on the kind of wood 

 and on the soil in which it is placed. In Idaho 4 in. x 4 in. wooden posts 

 used for lot corners, made of the best fir and painted, have been almost 

 completely destroyed in one year. There are a number of instances where 

 wooden pipes have gone to pieces in four or five years or even less. How- 

 ever, if the pipe is made of good selected material, free from sap wood, the 

 life should be from ten to fifteen years for a wooden pipe empty part of 

 the year. The life of wooden pipe which is kept constantly full and buried 

 to such depth as to prevent freezing, would be considerably greater, prob- 

 ably 20 to 30 years provided the soil in which it is buried does not contain 

 injurious salts. Were it not necessary to prevent the water in the pipe 

 from freezing, it is my opinion that the life of a wooden pipe kept constant- 

 ly full and under sufficient head for the wood to be saturated, would be 

 increased if it was laid above ground not in contact with the soil. 



As far as the cost of maintenance is concerned, a wooden flume system 

 requires frequent repairs, tarring, and calking, the cost of which would be 

 greater than the maintenance of a pipe system. 



It is impossible to represent numerically the above statements with any 

 degree of accuracy because of the varying conditions. Roughly they may 

 be represented as follows: 



Annual cost of wooden flumes and wooden pipes 1 given in per cent, of 

 first cost: 

 For wooden flumes, life 8 to 12 years 



Annual maintenance and repairs distributed over entire life. . 5 per cent. 



Sinking fund for renewals 9 " " 



Interest on capital invested 6 " 



Total .....20 " " 



For wooden pipes empty part of the time, life 10 to 15 years 



Maintenance and repairs 2 " 



Sinking fund for renewals 7 " 



Interest on capital invested 6 " " 



Total 15 " " 



For wooden pipes always full, life 20 to 30 years 



Maintenance and repairs 1 " " 



Sinking fund for renewal 4 " " 



Interest on capital invested 6 " 



Total 11 << 



These figures show that the annual cost which must be provided for to 

 maintain and renew a system and pay interest on capital invested is 20 per 

 cent, for a wooden flume system, 15 per cent, for a pipe system part of the 

 time, and 11 per cent, for a pipe system always full. These costs are in the 

 ratio of 1.8, 1.3 and 1. Therefore a flume system is more economical than 



