THE JERSEY CITY WATER MUDDLE.
THE blunder regarding the estimated capacity of the conduit supplying Newark and Jersey City with water is in all respects a serious one. It affects not only the cities supplied, but also the East Jersey Water Company. Of course, various reasons will be assigned for the failure. In our judgment none of them from an engineer’s standpoint of observation can be admitted as valid. A shortage of 15,000,000 gallons out of a total estimated delivering capacity of 50,000,000, (30 per cent, deficiency),will certainly excite more than passing notice, and particularly among hydraulic engineers. It is this line of thought which directs our consideration of the object lesson. Why should such a serious error as that of 30 per cent, deficiency occur in the calculation of the discharging capacity of a 48 inch riveted steel conduit in the face of the arbitrary figure of the ascertained head, length, and diameter of the conduit, and with the data comprising the usual coefficients of resistance to flow due to certain wellknown characteristics of friction in pipes before the eye of the engineer in charge ? It is possible that the new coefficient of resistance to flow in steel pipes, occasioned by riveting its cross and lengthwise sections together with lap-seams, has not been accurately determined. It has been asserted that the conduit leaked, and requires constant repairing. The main point after all is to show what measures of frictional resistance are due to the mechanical construction of a riveted steel pipe, as compared with a cast iron pipe. The present state of the art shows assuredly advantages of cast iron pipe in use over that of riveted steel conduits. The experiences in the use of the wrought iron or steel conduit at Rochester, after a period of several years, showed a diminution of flow due to accretions of vegetable growth, probably traceable to the peculiar chemical characteristics of the water of Hemlock lake. As no evidence exists that the East New Jersey conduit ever delivered 50,000,000 gallons of water as a test of its real estimated capacity, we can only say that the facts as stated point in the direction indicated as to the want of use of a proper coefficient of resistance to flow, due to the use of steel pipe as at present manufactured. The initial elements composing the factor of resistance, after a few years , use of a steel conduit similar in construction to the East Jersey conduit, will undoubtedly increase, if some remedy is not obtained to prevent accretions or deposits upon interior rivet heads and the edges of lap-seams. We think that steel conduits as at present constructed will in a shorter time present greater obstructions to flow than the obstruction;, due to tubercular formation in cast iron pipes.