12 BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 



tighter than where unseasoned lumber is used. The power used for 

 operating the small mill to cut out the necessary timber and lumber 

 to construct a flume is usually the ordinary portable type of boiler 

 and engine, sometimes in the combined form. There will be found 

 cases and localities in which the use of an overshot or an undershot 

 water wheel will more economically furnish the necessary power, 

 where there is an ample supply of water and favorable conditions for 

 Hs being used for this purpose, and there will be some cases in which 

 electric power to operate the mill, transmitted from a convenient 

 line of some electric-power plant, will be found most economical. 



After the mill is installed it is advisable to use prepared frames, 

 "forms," or miter boxes in cutting the brackets, frames, or arms 

 with the "power saw" into the desired length and shape, and also 

 in cutting the braces, stringers, sills, overlays, and material for use 

 in trestling. Experience has demonstrated that the material can 

 be shaped at the mill and transported to the place where it is to be 

 used by means of the water in the flume much more economically 

 than in any other manner. It is advisable to prepare the frames 

 and arms at the mill ready for setting up, and flume them in their 

 finished form down to the point where they are to be used; this 

 method requiring only that they be placed and fastened in position 

 after arriving there. (Fig. 5.) 



A CAREFUL SURVEY NECESSARY. 



An accurate and careful survey of the proposed line of flume con- 

 struction is a prime necessity and often a great economy. A need- 

 lessly expensive survey should always be avoided, but accuracy of 

 grade and careful and reliable "leveling" is imperative in order to 

 insure lasting flume construction. The equalization of grade is very 

 advisable wherever it can be accomplished without too great an 

 expense. And right here a practical knowledge of the comparative 

 benefits to be derived from having a steady or an even and moderate 

 grade, considered in relation to cost, is of great value. The grading 

 of soil in knolls or hillocks or ridges along the prospective flume line 

 is advisable up to a certain point, if necessary to maintain a reason- 

 ably steady grade for the flume. A careful preliminary survey fol- 

 lowed by a location survey, using a transit and level, will make it 

 possible to obtain a reliably constructed profile map which will show 

 to the prospective operator what the grading should be at different 

 points of his line. It is always best to know just what the grade 

 is going to be when completed, and approximately what it is 

 going to cost, before starting the construction work. No detailed 

 estimate of the cost of survey is included here, for the reason that 

 the wide range in conditions where flumes might be constructed 

 would make any set figures unreliable and possibly misleading. A 



