UTILIZATION OF SEWAGE. 45 



one inch in 1,500 feet, ten feet apart, and sloping banks 

 one inch to the foot on which is the vegetation. 



The use should in all cases be intermittent while the crop 

 is growing, that the ox3^gcn of the air may occcasionally 

 penetrate the soil, giving it a chance to breathe as it were. 

 But in winter, when vegetation slumbers, it may flow freely 

 over the land, where the fertilizing properties will accumu- 

 late without loss at or near the surface. Babut du Mares 

 claims that sewage in freezing eliminates these properties as 

 completely as salt water does salt in the same process, and 

 thus epuration is as perfect in winter as in summer. 



The highly productive farms of Holland are entirely sub- 

 merged during winter. The periodic overflow of the Nile 

 gives to the valley a reputation for natural productiveness 

 unequalled in any other part of the world. 



J. Bailey Denton says : " Every day's experience at Mer- 

 thyr has served to prove that with the most suitable free soil 

 it is hardly possible to overcharge them with liquids." 



It nevertheless is desirable there should be provision made 

 by the town or city for storm water by an overflow, or waste, 

 as the soil would otherwise be washed during heavy rains. 

 If there are no stagnant places in the ditches there will be no 

 odor, except where the trunk sewer first emerges from the 

 earth, where there will be some smell of fresh sewage. Re- 

 peated experiments in Germany and France have demon- 

 strated that in closed conduits decomposition does not take 

 place, and therefore there is no loss of fertilizing properties. 

 When, in the open ditches oxidation is so rapid, and the 

 deodorizing effects of the earth so powerful, nothing objec- 

 tionable is observed, — a fact which has probably been 

 noticed by all of you in the common earth-closet. 



The sewage should not come in contact with the foliage 

 of the plants. Tape-worm is said to be extremely prevalent 

 in Northern China and caused by the habit of emptying 

 foecal matter on the leaves of vegetation, and the eggs of 

 this animal are thus taken from one individual to be propa- 

 gated in another, and other diseases would be liable to a 

 similar mode of transmission. 



