2l8 AGKICULTURK OF MAIME. 



and I would not build one any smaller. It should be made of 

 concrete or any other substance which could be made tight; 

 but concrete is the cheapest and it is there for all time, while 

 lumber rots out and metal rusts out. It should be covered with 

 a reinforced concrete slab, and then you can just forget that it 

 is there, so far as ever having to go near it again is concerned. 

 Perhaps what goes on in the septic tank ought to be discussed. 

 When the sewage goes in, being heavier than the liquids there, 

 it settles to the bottom and there the anaerobic action takes place. 

 These bacteria absorb the animal and vegetable matter in the 

 sewage, and in the absorption multiply themselves, and gas 

 forming bacteria and water are the result. The gas forming 

 bacteria, being lighter than water, go to the top and form a 

 brownish green scum. I have seen it two or three inches deep 

 after a few years of use. Between this green scum at the top and 

 the solids at the bottom there is a clear liquid known as the 

 effluent. At the point where it is clearest this should be taken 

 out, because if you empty a gallon into a tank after the tank is 

 full, a gallon must go out. Experiments have shown that a pipe 

 about 12 inches down from the top will accomplish this the best. 

 The inlet pipe should have an elbow which would deflect the 

 sewage downward so it would not flow across and go out be- 

 fore it is treated. The bottom of this pipe should be i8 inches 

 down from the top of the tank and i8 inches up from the 

 bottom. Then the question is. How do you get the effluent out 

 at a point higher than it comes in? The source is always higher, 

 and the source forces it up and out. The sewer pipe should 

 be tight, of course, and it should go to a point about a rod 

 from the top of the tank on about a level so that it may make 

 a quick descent, because the liquid will back up in the inlet 

 pipe until it goes back to the level of the bottom of the outlet 

 and you can readily see that if you have a long and gently 

 sloping descent, it would not be very long before there would 

 be trouble with stoppage. The inlet pipe should never be less 

 than four inches in diameter and the outlet pipe should be 

 from three to four inches, the inlet pipe going to within a rod of 

 the tank and then quickly descending, and the outlet pipe not 

 tight but with loose joints because you want to get rid of that 

 water as quickly as possible. While the water is almost as 

 good as the average drinking water in the city, there are still a 



