ON THE TREATMENT AND UTIIIZATION OF SEWAGE. 181 



aged, more sewage is applied tiian can be purified by the surface-flow, even 

 when tbat takes place through thick vegetation (as in the case of the samples 

 from the fields of Italian rye-grass on the northern farm), and miich more 

 than can be purified under less advantageous conditions (as in the case of 

 the samples from the field of mangolds on the southern farm, although the 

 water from this field was mixed with that from two of meadow-land) ; and 

 they show, too, that the valuable matters that are not utilized are not only 

 thrown away, but are thrown away in their crude condition, not having been 

 subjected to the oxidizing action necessary to convert them into innocuous 

 nitrates and nitrites. 



Lastly, we must notice the fact that the temperature of the effluent water 

 of the northern farm is only slightly (less than one degree Fahr.) below 

 that of the sewage, while the effluent water of the southern farm is actually 

 half a degree Fahr. warmer than the sewage. This clearly shows that the 

 sewage has not been subjected to the cooling which percolation through soil 

 entails. 



(h) Ohservatmxs on ilie Sewage-Fann at Earlswood designed for the 

 Utilization of the Sewage of lied Hill and Eeigate. 



This sewage-farm consists of about 70 acres of Earlswood Common, of 

 which, it was stated, about 50 acres abutting on a tributary of the river 

 Mole have been laid out for irrigation. It is intended very shortly to add 

 more land to that already prepared from properties adjacent. 



The soil is for the most part a clayey loam. The higher ground next the 

 Common is rather freer in character, while the lower part appears to increase 

 in density as it nears the outfall. 



The surface, which has rather a steep fall in its higher part, gradually be- 

 comes more level as it descends, and has a very slight fall indeed as it ap- 

 proaches the outfall. 



Before the sewage is delivered to the land for irrigation it passes through 

 one of Latham's patent extractors, an ingenious invention for the separation 

 of the solid from the liquid parts. The liquid sewage is delivered from the 

 extractor by covered conduits, from which it is directed right and left into 

 the highest carrier. The land laid out for irrigation is divided into three 

 series of beds or slopes separated by roadways, on the upper side of each of 

 which is a surface-drain to receive the effluent liquid as it passes off the beds 

 above, and on the lower a main carrier to deliver the sewage for distribution 

 to the series of beds below. The three series are divided rectangularly into 

 nearly equal-sized blocks, to be again subdivided by minor or inner carriers, 

 laid out partly on the catchwater and partly on the ridge-and-furrow form. 

 The surface of the highest land of the uppermost series of beds is about 2-1 

 feet above the surface of the lowest land in proximity to the outfall-stream. 



None of the land is underdrained, and the lowermost beds appear to be in- 

 capable of uuderdrainage at a sufficient depth unless the stream receiving the 

 water to be discharged is appropriately deepened at very considerable cost. 



In answer to inquiries, it was stated that after heavy rains the lowest 

 portions of the irrigated lands are swamped by the backing of the water 

 Avhich collects on their surface when the soil itself is in a state of complete 

 saturation. At the time of the inspection by the Committee (July 11th), the 

 sewage had collected in pools on the surface of the irrigated beds in a man- 

 ner injurious to the crop under treatment. The work of irrigation is designed 

 so that the sewage applied to the higher land may be reapplied on the sur- 



