MODERN SEWER CLEANING.
Berlin, Germany, is in the foremost rank among municipalities for the thoroughness of its system of sewerage and sewage disposal. Its population, including the suburbs, is about 1,600 000, and its area 15,586 acres. Up to 1874 it had no sewerage system. In 1894 the total length of its sewers was 462 miles, and over 22,000 acres of land was cmbracedjin the tracts used for purifying the sewage of the city. The construction of the works has been followed by a fall in the death rate from 32 to 20.2 per 1,000. “ The most surprising feature in this great work,” according to M. I.aunay, the engineer above mentioned, is the rapidity with which it was planned; the methods, once studied cut and adopted, have been followed without long or futile discussion with that force of will, that calm perseverance, that strong stubbornness, and, in a word, that spirit of discipline which is marked in the the German character.”
The sewers of the city generally are cleaned once in every period of tnree nights and four days. The pipe sewers are flushed once in three days; one night answers for the examination of the masonry sewers, and for the other three nights the pipe sewers are being cleaned by the passage of a special broom through them. This somewhat antiquated method of cleaning has of late years given way to an automatic flushing device. This is essentially a dam made of planks and cut to conform nearly to the section of the sewer. This dam is made in sections, united by bolts, for convenience in passing it into the sewer, and is provided with rollers above and below, and is kept in an upright position by a rear brace and guide rollers. It acts as a dam.and permits the water to escape under a head through the opening at the bottom, cutting away and driving before it the sand in the sewer. This device is especially serviceable in the sewers under 2 1-2 feet in height, into which it would be difficult for workmen to enter. Another new de/ice, is also being used in clearing the pipe sewers on a similar principle. In this the plank dam is replaced by a cylindrical dam,having a section equal to 3-4 of that of the pipe. To keep the open sec tion down and to guide it, three heavy balls are made to roll in the bottom part.