LECTURES AND ESSAYS READ AT INSTITUTES. 



37a 



THE LOCATIOK OF DKAINS. 



So far as possible, drains should be located, in such a manner that the water 

 will flow with greatest velocity, provided, of course, the velocity is not so great 

 as to injure the stability of the drain ; this, I think, practically never happens. 

 The greater the velocity the smaller the size of the pipe needed, and the less 

 the cost of the work. The application of this rule would require the drains 

 to run directly down all slopes, and that is about the only important principle 

 to be borne in mind in locating drains, and should be applied whenever appli- 

 cable. As an illustration I refer to Fig. 5, which is a sketch map not drawn 

 to scale, of the drains actually constructed in the west part of the grounds of 



Rural New-Vu r k er. 



PLAN OF LOCATING DKAINS. FIG. 5. 



the Agricultural College at Lansing, Mich. The outlet is protected by a stone 

 wall at 0, the main drain of four-inch tile passes up the valley, changing 

 direction with it to E, a distance of 33 rods, having an average fall of two 

 inches per rod. At this point the contour of the ground required an abrupt 

 bend, and a silt basin, the construction of which will be described further on, 

 was sunk at this point, principally to lessen friction from the abrupt bend, 

 also to allow the workings of the drain to be examined, and retain silt from 

 drains 12 and 13. From the silt basin a sub-main, marked 12 in the cut, was 

 run, which received a number of laterals making an angle of forty-five degrees 

 with the main, each terminating at the summit of the ridge. 



From the main D, a series of laterals, marked, 1, 2, 3, 4, etc., were run 

 directly up the slope; the angles made with the main drain being likely 

 to make back currents, they were connected with the main by curves, asshown 

 in the plan. Between drains 5 and the ends of 1, 2, 3, and 4 was a terrace, 

 which it was impossible to pass through, and drains 5 and G were put in run- 

 ning diagonally down the slope. The sizes of the tiles used were, for main 

 drain, four-inch ; for drain No. 12, three-inch ; for lower part of 13, three-inch ; 

 for the remainder of the drains, two-inch ; area drained about twelve acres. 

 The fall of the drain marked 12 was two inches per rod. The fall of the short 

 laterals was often as much as four to six inches per rod. The foregoing exam- 

 ple was chosen, not for its perfectness of detail, but as one which, although on 

 35 



