6 JULY 1867, Page 23

The Sewage Question. By Frederick Charles Kropp. (Longmans.)

—It is amusing to see how each new writer on sewage pooh-poohs his predecessors, and while proving the absolute perfection of his own sys- tem, cuts away every inch of ground from under their feet. But while giving the new corner a short lease of infallibility, this process is sure to entail his final ruin. The next man serves him as he has served those who went before him, and at the best he is "the priest who slew the slayer, and shall himself be slain." Meanwhile, we do not approach

any certain decision on an all-important matter. We should have esteemed Mr. Krepp's work the more if he had not disposed of all existing systems, from the main drainage to Mr. Moule's earth closets. His own system looks very complete, is certainly neat and handy. But

some of the chemists or engineers whom he has criticized will retaliate, and a man's project looks very different in his bland convincing own pages and in the fierce light of hostile criticism. We must allow for- the possibility of the belt arrangements getting out of order, and we must look to the possible results of such an accident. As Mr.. Knepp does not intend in any way to deodorize the sewage, as he. banishes both earth and water from his air-tight pipes, any escape from them would be pestilential. We do not profess to bo scientific enough to understand or explain the "pneumatic sewerage system," on which Mr. Kropp relies, but we must do him the justice to admit that till the hostile criticism of rivals and predecessors and successors touches him, he is armed at all points. He has his plan for connect- ing all London houses with subterranean reservoirs of iron ; his plan, for shutting off the gases from each house by means of hermetically closing valves ; his plan for emptying all the branch pipes into the- street reservoir by an air pump with a movable steam-engine ; his plan for emptying the street reservoirs by the same process, and carrying) off the manure in a tender to the lands which need its fertilizing pro- perties ; his plan for ploughing furrows for the manure, filling them, and covering them over, all in the same movement and with the same- machine. Whether these schemes are practicable or not, they are most ingenious, and Mr. Kropp has explained them so fully and collected so many facts bearing on all branches of his subject, that his book deserves. to be studied.