Town Sewage. 481 



advantage ; but in that case the sewage would be very inade- 

 quately utilised and purified. 



The Table leads to the following practical suggestion : that 

 with an application of about 5000 tons of average sewage per acre 

 per annum, applied pretty evenly throughout the year, taking the 

 average of soils and seasons, an average of about 30 tons of 

 grass might be expected. Assuming such a produce, and 

 allowing 4/. per acre for rent or natural yield, 



d. 



The grass, if sold at 10s. per ton, would pay per ton of sewage 0*5 



12s. Qd. „ ■ „ 0-7 



,, ,, los, „ „ O'J 



This would be the gross return from which the cost of the 

 application of the sewage, other expenses of the crop, and the 

 farmer's profit would have to be deducted, before anything was 

 available as payment to the town. 



In comparison with the result here assumed it may be ob- 

 served that in the neighbourhood of Croydon, where about 250 

 acres are laid down for sewage irrigation, and where there are 

 probably more than 6000 tons of sewage annually available for 

 each acre, from 25 to 30 tons of meadow grass, selling for from 

 20/. to 25/., are obtained per acre per annum ; and after 

 deducting as before 4/. for rent, the gross return per ton of 

 sewage employed is from 0'6d. to 0'8d. With a somewhat 

 similar application to Italian rye-grass, 30 to 35 tons, selling 

 for from 25/. to 30/., are obtained, yielding, after deduction for 

 rent or natural produce, from O'^d. to Id. per ton of sewage 

 employed. It will be observed that in these cases the selling 

 price of the grass is 16^. or 175. per ton : but it is obvious that 

 if sewage were extensively employed for the production of grass, 

 its present price could not be maintained. 



A marked effect of liberal sewage irrigation (indeed of 

 active manures generally) on the mixed herbage of grass land, 

 is greatly to develope the Graminaceous plants, nearly to exclude 

 the Leguminous, to reduce the prevalence of miscellaneous or 

 weedy plants, but much to encourage individual species ; among 

 the grasses the rough meadow grass, couch grass, rough cock's- 

 foot, woolly soft grass, and perennial rye-grass are frequently 

 very prevalent. But, sewaged produce being generally cut or 

 grazed comparatively young, the tendency which the great luxu- 

 riance of a few very free-growing grasses has to give a coarse 

 and stemmy later growth is not an objection, as in the case of 

 meadows left for hay. 



The chemical examination of the grass grown at Rugby, 

 with and without sewage, showed that at the usual time of cutting 



