24 On the Principles and Methods [Jan., 



1. The Hose and Jet System. — The fatal objection to this 

 system is that it is not capable of application at all seasons. In 

 laying out works for the purpose, the sewage must, in the first 

 instance, be brought into the field by means of underground pipes, 

 which must also be laid in a sort of network over the whole grounds 

 to be manured, to which pipes with couplings or hydrants for 

 attaching a hose are fixed at certain points (see Yignette). In all cases 

 where the hose and jet system is applied, the sewage must be deli- 

 vered under pressure to enable it to be distributed over the field at a 

 considerable altitude above its surface, as well as to overcome the 

 friction in the pipes, and a head of from 10 to 12 feet is necessary 

 where the sewage is delivered by the force of gravitation. Where 

 a natural fall cannot be obtained, pumping becomes necessary, and 

 this adds considerably to the cost. One great objection to the hose 

 and jet system is that sewage cannot be applied to crops by it 

 except at the earliest stages of their growth, owing to the necessity 

 for dragging long lengths of hose over the land ; it is therefore 

 quite inadmissible when the crop has grown to any considerable 

 height. Besides, by this mode of application the sewage is sprinkled 

 over the crops, falling upon them as a shower, instead of being 

 applied to the roots, which, though it would be unimportant and 

 harmless were pure water only used, becomes actually injurious to 

 vegetation in the case of sewage irrigation, by leaving certain de- 

 posits upon the leaves and stems of plants, which clog their pores 

 and check growth. The system has enjoyed a partial success on 

 the farms of Mr. Alderman Mechi and Sir. Nelson, but at Rugby, 

 and other places, it has totally failed, and been abandoned. Mr. 

 Eawlinson has stated that it would cost more to distribute 500 tons 

 of sewage per acre by the hose and jet than it would to apply 

 5000 tons by surface channels. 



2. Sub-Irrigation. — Under this system porous pipes, or tubes 

 perforated with small holes, are laid under the ground at such a 

 depth as to be beyond the reach of the plough, through which the 

 sewage-water is forced. In some instances the pipes that are used 

 for drainage may be made use of for this purpose by merely stop- 

 ping up their outlets during the time that they may be required 

 for irrigation, by which means the water will be dammed back 

 until it reaches the upper stratum of the earth and the roots of 

 the plants. This system has been practised in Switzerland to a 

 limited extent ; it is, however, expensive, and is open to the objec- 

 tion that it tends to raise the water in the land to the level of the 

 soil, and the earth thus becomes water-logged, in addition to which 

 it is attended with a great waste of fertilizing matter owing to the 

 depth at which the sewage is delivered below the surface, a part 

 of it gravitating still lower into the earth, and only a portion 

 reaching the roots of the plants. 



