68 ANNUAL OF SCIENTIFIC DISCOVERY. 



after passing ten discs, gave a jet only one-ninth as high as after 

 passing one. 



The Chairman remarked that the principle of retardation, here 

 illustrated, had been applied to the pistons of pumps, by cutting 

 around the piston a series of grooves close to each other, thus form- 

 ing what is called a water packing. It was said, however, not to 

 work as well as was at first expected. Not long since a case oc- 

 curred at the Jersey City Water Works relating to the subject now 

 under discussion. It became necessary to lay down, under the 

 Hackensack River, for the distance of 1,000 feet, another main pipe 

 of 36 inches internal diameter. Mayor Cleveland of Jersey City, 

 then a Water Commissioner, made some important experiments to 

 prove that water was greatly retarded wherever turned from a right 

 line, even if the pipe be enlarged on the curves. 



Mr. Dixon said the proposition was to lay under the river a pipe 

 which would adjust itself to the bottom by means of from 14 to 18 

 movable joints. The position of the pipes, on either side of a joint, 

 may be illustrated by supposing two common clay smoking pipes to 

 be laid down in opposite directions, so that the mouths of their 

 bowls would come together ; these being fastened by a collar, they 

 would be free to move up or down, and thus such pipes would adjust 

 themselves to the bed of the river. Mr. Cleveland objected to this 

 ' plan on the ground that the pipes so laid would not deliver the quan- 

 tity required, because the curves would impede the ilow of the water. 

 In order to remedy this, the contractor proposed to enlarge the pipe 

 at the curves, from 06 to 46 inches in diameter, the pipe being 

 brought down to its original size between each curve. This propo- 

 sition was approved by several prominent engineers. Mr. Cleve- 

 land objected to these enlargements ; he believed they would in- 

 crease rather than diminish the evil complained of. In order to 

 demonstrate his statement, he made the following experiments : 

 First, he constructed a straight pipe of lead, ;>6 inches long and one 

 and a half inches internal diameter; second, he made another pipe 

 extending the same distance, and containing two curves, so as to 

 carry the water in a direction perpendicular to its first course, then 

 asrain in first course, thus turning tAvo right angles. The diameter of 

 the ends of the pipe was \h inches, and that of the curved part was 

 1 11-ljJ inches. Parallel lines drawn through the center of the two 

 ends were just 2^ inches apart. Third, he constructed another pipe 

 containing four curves, the two curves, additional to those in the 

 second pip", were to bring the water ba ; -k, so that its entrance and 

 discharge, were in the same right line. The curves in the third pipe, 

 were of the. same diameter with those in the second pipe. The pipe 

 between e:ieh two curves, as well as at each end. Avas 1 inches in di- 

 ameter. These pipes were constructed with the greatest care; the 

 ciirv'.-s were fitted in halves over wooden forms, and soldered on the 

 ourside, the inside being made so smooth as to leave no crease at the 

 joints. A tank of water was prepared <~) feet 'J;; indies in diameter at 

 the top, and two feet deep. A hole was made on the side at the bot- 

 tom, into Avhich each of the pipes was in turn fitted. The object be- 

 ing to discharge precisely the same quantity of Avater through each 

 pipe, tAvo inarlts Avere made on the inside of the tank, the upper one 



