THE KENNEDY PIPE SCRAPER — DOANE. 447 



and similar scrapers have been in use in this city ever since that 

 date. Mr. Kennedy is usin^ them in many cities in Europe 

 under his own supervision. Mr. Keating made an improvement 

 in the cutter or scraper. The spring which presses the cutting 

 edge against the pipe and the cutter itself were in one solid 

 piece on the imported scraper. Mr. Keating made the cutter 

 detachable, and it can be replaced when worn by use. The 

 scrapers are made in all sizes, from six inches to twenty-four 

 inches, and weigh from 100 lbs, to 1,000 lbs. 



The principal parts of the scraper are of iron or steel. The 

 forward end is provided with eight cutters or scrapers so 

 arranged that the whole inside surface is cleaned by their pas- 

 sage through the pipe. Two pistons of sole leather serve to 

 steady and guide the scraper and the pressure of the water 

 against the rear piston forces the machine ahead. The normal 

 pressure of the water under gravity in our system has been suf- 

 ficient to propel the scraper without aid from other quarters. 



A section of pipe is cut out at each end of the mains, leaving 

 an opening of sufficient length to admit the scraper. The 

 machine is inserted at the end nearest the source of supply and 

 the pipe replaced, the joints being made with a split thimble or 

 sleeve. When all is in readiness the water is turned on and the 

 scraper starts off with a I'umbling noise by which it can be 

 easily followed. The rate of speed varies from one quarter of a 

 mile an hour on a flat grade under a small head of water, or 

 going up a hill, to one mile in ten minutes going down hill. 

 Where there are hydrants or blow-ofis they are left open and 

 the approach of the scraper may be detected first by a current 

 of air followed b}^ a rush of water which has accumulated in 

 front of the machine. The water turns to a dirty brown color 

 and as the scraper passes it is as black as ink. The pressure 

 then increases rapidly, and if the water is allowed to run from 

 the hydrant it gradually becomes clear. The hydrants are 

 usually closed at once, however, so that the pressure on the 

 scraper may not be reduced. 



Pipes should be cleaned every year, as each succeeding forma- 

 tion becomes harder to remove. The greatest length of pipe 



