AMERICAN INSTITUTE. 419 



the water will flow out until that above the level of the lower 

 side of the buug-hole is entirely removed, except so much as is 

 held by capillary attraction. The water which has passed out 

 is not all of it that which was originally above the level of the 

 outlet, for that water did not take a diagonal direction toward the 

 outlet from all parts of the upper half of the barrel. Its weight 

 carried it directly down, and caused it to force up that which was 

 below until it passed off" by the outlet. Probably, for a short 

 distance i'rom the hole, the water moved in a slanting direction; 

 but this is only local, and does not invalidate the illustration. 



Now, if we pour more water into the' barrel, iu imitation of a 

 heavy shower, it is at once absorbed by the soil in the upper part 

 of the barrel, and it passes down as before, raises the water level 

 to a point above the lower edge of the bung-hole, and the outflow- 

 ing again commences. Here we see that the water passes out as 

 soon as it reaches the lower part of the outlet, and (except for 

 the removal of water close to the side of the barrel) it would not 

 accelerate the flow to enlarge the hole on its upper side — sup- 

 posing it originally large enough to carry off the water as fast as 

 it settles and raises the level. The same is the case with the soil. 

 The position of the lower side of the tube which is formed by the 

 tile decides the water level; and whenever from rains or any 

 other source water is given to the upper soil,, it passes down in a 

 vertical direction, and raises the level until ^ like amount passes 

 off through the tile. It may move sideways for a foot or two 

 each way from the drain, but this does not affect the principle. 

 When a cubic inch of water falls on the soil at a point midway 

 between two drains, it does not travel along until it finds an out- 

 let, but it passes down to the level of the water below, and by its 

 weight it causes a rise in the whole mass until, other thmis being 

 equal, a corresponding amount of that which is in the immediate 

 vicinity of the drain passes out. Hence we see that water enters 

 the tile almost entirely from below; and in view of this fact it is 

 obvious that all that is necessary in practice is to so lay the tile 

 that it will carry oft' the water thus received. Filling in the 

 ditch above the tile is entirely useless in all cases where the tile 

 is large enough to carry off the water — and it should of course 

 be always so — for it does not at all facilitate the entrance of water 

 into the drain. If there were any loose material needed it should 

 be placed below the tile, for it is from below that the water comes. 

 But it is never needed. Lay your tile so that the water will run 

 out, and you cannot keep it from running in. 



