Town Seicage. 



227 



lias done no otlier service, it has at all events rendered some benefit to 

 tlie country, by carefully gauging tbe sewage of Eugby. For nearly 

 three years the sewage of that town, which is collected in a large reser- 

 voir tank, has been sampled, and samples of it have been transmitted 

 almost weekly to Professor Way for analysis, and in a table before 

 you you see some of the results. The composition of sewage is, 

 for convenience sake, estimated by chemists according to the number 

 of grains of ammonia per gallon which it contains. If you look at 

 Table I. you will observe that in 18G1, 1862, and 1863 the composition 



Table I. 



Variation in the Composition of the Eugby Sewage at different times. 



varies very much indeed at different periods of the year, and also somewhat 

 in different years, the highest amount of ammonia in 1861 being 15^ 

 grains, and the lowest about 3 ; the highest in 1862 about 11^, and the 

 lowest about 2^; and the highest in 1863, 12f, and the lowest 3 ; but 

 taking the mean of the three years, you will find that the variation is not 

 very great, the amounts being respectively about 5^, 6, and 7 grains. In 

 1862, which was the year when the amount of ammonia was lowest, 

 there was the greatest amount of rain; and I should observe that 

 Bugby is a town which has been sewered upon the modern principles. 

 In Table II. (p. 228) you will find that with 60 tons of water per head 

 per annum the sewage-water is estimated to contain 6^ grains of 

 ammonia per gallon ; this is the quantity which is found in the 

 Rugby sewage, and the water supply and rainfall are there estimated 

 at about 60 tons per head per annum. Further on you will see the 

 calculated quantity of ammonia in each gallon of sewage, where the 

 rainfall and water-supply amount to 70, 80, 90, and 100 tons per head 

 per annum. I believe the average sewage of the metropolis will 

 approach the latter amount. 



And now comes the question. How are we to apply this sewage to 

 grass, or to arable land ? The authorities on the subject, those, I mean, 

 who have ^^Titten or spoken with any acquaintance with it, and whose 

 opinions may therefore be regarded as having some weight, have 



Q 2 



