SIZE OF TILE. 171 



Mr. : Is muck hay as good as other? 



Prof. Carpenter: Timothy and red-top raised on muck are as good as 

 any. 



Mr. Graham: If muck is deep would you put drains below it? 



Prof. Carpenter : If not more than 3 to 5 feet ; yes. 



Mr. Lester : Would an opening 40 rods from the lower end of a tile drain 

 to admit air facilitate the flow of water? 



Prof. Carpenter : Grenerally there would be no need of it. 



Mr. Peabody: What size tile would drain 10 acres with one inch fall per 

 rod? 



Prof. Carpenter : Four-inch tile. We drain 50 acres with 8-inch tile, but 

 that is more than ought usually to be expected of 8-inch tile. 



Mr. : Why does muck hold water when it is used to fill up a tile 



ditch? 



Prof. Carpenter : It has become puddled. 



Mr. : I think it closes the joints of the tile and so keeps the water 



out. 



Prof. Carpenter : Water usually enters tile from below. It is better that 

 it should do so. We cover joints with sod or broken tile. 



Mr. : Do you ever place silt basins? 



Prof. Carpenter: Yes; but I doubt their value. I think the silt would 

 wash right down through. They are good as observation stations to enable 

 one to see the workings of the drain. 



We dig a hole two feet below the line of tile and brick up the sides, put- 

 ting a 16-inch tile over all. Have the outlet lower than the inlet. 



Mr. : Is marsh hay good to cover joints of tile? 



Prof. Carpenter : Yes ; but not as good as sod. 



SIZE OF TILE. 



BY PKOF. R. C. CARPENTER, LAKSING, MICH. 



There are two things to be considered, first the ability of the tile to carry 

 water, and second the vrater supply itself, which must be removed. The 

 first consideration has been solved quite accurately as applied to smooth iron 

 pipes, wooden pipes, earthen sewer pipe, and even brick sewers. ' ^ 



The best statement of the case is to be found in Weisbach's largg treatise 

 on Mechanics. We will only quote results. The theories give rules with 

 co-efficients depending on experiment, which have been tested extensively 

 by actually measuring the discharge from given pipes, under certain con- 

 ditions. 



The following formula, although not possessing all the refinements of 

 some of the later formulas, is still quite accurate for long lines of pipe. I 

 have tested it myself once with six-inch tile, and once with an inch iron pipe, 

 measuring the discharge. The results were very close indeed to the formula. 



Formula for discharge: — 



Q = 39WW 



Q = discharge in cubic feet per second. 



