THE FARMER'S MAGAZINE. 



value of sewage in irrigation, or that of its merely 

 mechanically or chemically combined portions. 

 This examination may be, perhaps, the more valu- 

 able, since there is still a considerable general 

 confusion of ideas with regard to the agricultural 

 value of sewage, and the most profitable mode of 

 applying it to the soil. 



The startling amount of the sewage of our great 

 towns is but little understood ; let us confine our 

 attention on this occasion to that of London. The 

 bulk of the metropolitan sewage may be approxi- 

 mately estimated by that of the water used by the 

 inhabitants. Now, this was ascertained in 1850, 

 by the officers of the General Board of Health, and 

 is given in their report on the supply of water to 

 the metropolis, when they remark, p. 10. — 



" The gross daily quantity of water pumped in- 

 to the metropolis amounts, according to the ob- 

 tained returns, to upwards 44,000,000 gallons. In 

 order to give a conception of the quantity of water 

 thus dehvered, it may be stated, that the daily sup- 

 ply would exhaust a lake equal in extent to the 

 area of St, James's Park, 30 inches in depth ; that 

 the annual supply exceeds the total rainfall of 27 

 inches over the popidated portion of the metropolis 

 (25 square miles), by upwards of 50 per cent., and 

 that it would cover an extent of area equal to that 

 of the city {or about one square mile), with upwards 

 of 90 feet depth of water. 



" The daily supply would, however, be delivered 

 in 24 hours, by a brook 9 feet wide and 3 feet deep, 

 running at the rate of 3 feet per second, or a little 

 more than two miles per hour; and three sewers of 

 3 feet in diameter, and of a proper fall, will suffice 

 for the removal of the same volume of refuse or 

 soil-water. The total weight of this annual supply 

 of water is nearly 72,000,000 tons. The daily cost 

 of raising the whole quantity by engine power 100 

 feet high, would be about £25 or about £9,000 per 

 annum. 



" The average daily quantity pumped into the 

 districts, exclusive of the supplies to large consu- 

 mers, and of the quantity used for all public pur- 

 poses, would, supposing it were equally distributed 

 for each house, occupy about 50 pailfulls, and 

 would weigh about 13 cwt." 



In urging the removal of the great mass of de- 

 composing sewage matter, whose bulk is thus in- 

 dicated, the Commissioners allude to some of its 

 injurious effects, which will not be unworthy of 

 my reader's notice, in regard not only to their own 

 health, but to that of their domestic animals. They 

 observe : — 



"' In a state of nature animals will not, when at 

 liberty, remain near or sleep over their own drop- 

 jiings. Some animals are endowed with instincts 

 to cover them up. When attention is pai<l to the 



proper keeping of animals, it is found to be inju- 

 rious to allow them to lie amidst the fumes of their 

 own dung. Formerly the Zoological Society suf- 

 fered heavy losses among the animals kept at Re- 

 gent's Park from neglect of this law, as, e. y., in 

 the case of the carnivora, which were originally 

 confined in a roofed and. enclosed building, the at- 

 mosphere of which, during a single night, became 

 strongly impregnated with ammoniacal exhalations* 

 A marked improvement has followed the keeping 

 of the same order of animals in dens exposed to the 

 open air, together with the practice of immediate 

 removal of the excrement. Skilful trainers of 

 horses for hunting and racing have their stables 

 carefully cleansed, and all dung as well as the urine 

 removed, three times a day, to such a distance that 

 no fumes from them may reach the animals. But 

 the common practice in towns is to keep the dung 

 in the stables for weeks, during which time not 

 only the animals, but the neighbourhood, are sub- 

 jected to insalubrious eflfluvia, the effects of which 

 are strikingly visible in the palhd countenances and 

 inferior stamina of the grooms and stable boys; 

 On an investigation of the disease among hunting 

 dogs, called " kennel lameness," it was found that 

 mere change of the sites of kennels did not avert 

 it ; and eventually its cause was ascertained to be 

 defective cleansing, including the want of a due 

 supply of pure water, and of effectual drainage, A 

 person having much experience on the subject lays 

 it down as an axiom, that the removal of all foul 

 matters from within or beneath the kennels, must 

 not only be constant and complete, but distant ; 

 and that no opening of a drain should be allowed 

 within at least 100 yards of the kennel," 



This amount of water supplied to the metropo- 

 lis (which has been materially enlarged since 1S50), 

 nearly represents the whole bulk of the London 

 sewage; since, although reduced by evaporation, 

 it is most considerably enlarged by the drainage of 

 the rainfall and springs. 



To worse than waste this enormous amount of 

 liquid manure, by pouring it into the Thames has 

 long and justly been deemed a gross absurdity ; 

 but how that national loss of fertilizing matters 

 shall be best applied to an agricultural purpose is 

 not so generally understood, although it has been 

 the occasion for the display of very considerable 

 discussion, of illinformed zeal, frequently mingled 

 with personal vulgarities, not unworthy of those 

 very sewers. 



There have been two modes suggested for the 

 utihzation of the fertihzing matters of sewage. 1st. 

 That of precipitating its solid portion, as at Leices- 

 ter, and one or two other places ; and 2ndly, by 

 using the sewage (in its ordinary state, or after 

 being deodorized), in irrigation. 



