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



consideration the possibilities of such features being needed when 

 locating the general line along winch his flume is to be constructed. 



Where such features are carefully looked up before the final location 

 of a flume line is settled and flume construction has begun, it is some- 

 times possible slightly to vary the location of the proposed flume fine 

 so as to bring it to the desired grade to be successfully operated in 

 connection with a cheaply constructed holding reservoir, without in 

 any way decreasing the transporting capacity of the flume. It is also 

 sometimes advisable to construct a small reservoir or " catch basin" 

 at the foot of an unavoidably long and very abrupt grade, so that 

 when the material being shipped leaves the flume or slip it will strike 

 into a pond of water and thus avoid being split or broomed. Some- 

 times the reservoir and its additional feeders will furnish enough water 

 to permit the flume line to be carried on an even grade from the point 

 of the " catch basin" or small reservoir at the foot of an abrupt 

 descent to its destination. In such cases the reservoir and feeders act 

 as equalizers of the volume of water in the flume. 



It has been found necessary in some instances to have small storage 

 reservoirs, provided with a small gate that could be quickly closed or 

 opened, located at different portions of a flume where no feeders were 

 available, in order to obtain a sufficient volume of water to carry the 

 material being handled to the next station or reservoir, or to its desti- 

 nation. Where conditions obtain that make this kind of an operation 

 necessary, it is usually advisable to have the mouth of the "intake" 

 considerably wider than the flume, which permits the water to go into 

 the flume opening in a wide unobstructed flow. 



When operating under such conditions it is always advisable to let 

 the water in the flume run for a short time before any material is 

 shipped. Otherwise the material receives a strongly accelerated 

 movement on the rapid descents, and is therefore carried by its own 

 weight and momentum into the slower moving volume of water in the 

 flat grades at a greater rate of speed than the water is moving, and 

 consequently runs slightly faster than the water. For this reason 

 the water should always be allowed to run in the flume for a sufficient 

 time to be sure that the latter will be filled its whole length, or at least 

 to the next station below, before any material is started on its way 

 from the shipping point above. 



RESERVOIR PONDS AT HEAD OF FLUMES. 



It is advisable and oftentimes necessary to make a small artificial 

 pond or reservoir at the upper end of a flume in which to "land" or 

 "bank" the material to be shipped, especially when handling logs, 

 railroad crossties, or heavy unmanufactured material of any kind. 

 Conditions sometimes make it possible to use the ice on a pond of this 



