PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 



American Institute Polytechnic Association, 

 June IQth 1864. 



Chairman, Prof. S. D. Tillman; Secretary, Mr. B. Garvey. 



Hydraulics. 



Mr. J. B. Root explained, with the aid of diagrams an experiment made 

 hy him in relation to the flow of water through irregular tubes. He con- 

 istructed a tube of tin SO inches long, and 2| inches in diameter. Within 

 this tube were soldered 11 diaphragms or discs, at regular distances from 

 ^ach oth-er. In €ach circular disc there was a hole five-eighths of an inch 

 in diameter, the center of which was the center of the disc. Half way 

 from each disc the tube was perforated on the upper side by a very small 

 hole. One end of this tube was inserted into a bulkhead about nine feet 

 below the surface of the water. The object of this apparatus was to 

 measure the retardation of the water, in passing through the discs, by 

 means of the hight of the jets sent through the small holes on the top of 

 the tube. The jet from the first hole was about two feet high ; the next 

 jet was lower, and so on to the last hole, from which the water barely oozed 

 ■out. The rate in decrease in hight was directly as the number of discs 

 inserted — that is, the water after passing ten diacs gave a jet only one- 

 ninth as high as after passing one. 



How Change in Direction Affects the Flow of Water. 



The Chairman remarked that the principle of retardation, here illustrated, 

 liad been applied to the pistons of pumps, by cutting around the piston a 

 series of grooves, close to each other, thus forming what is called a water 

 packing. It was said, however, not to work as well as was at first expec- 

 ted. There is need of more light on the action of water in tubes« The old 

 experiments of Venturi reappear in all new works on hydraulics,, with but 

 little additional information in the same direction. Not long since, a case 

 occurred 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 

 whenever turned from a right line, even if the pipe be enlarged on the 

 curves. Doubtless the member from Jersey now present could enlighten 

 the association on this subject- 

 Mr. Diron 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 illus- 

 trated 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 quantity required, because the curves would impede the flow 

 of the water. In order to remedy this, the contractor proposed to enlarge 

 [Am. I>;st-] V 



