For special uses we are prepared to build COMPRESSORS to deliver air or gas at any pressure that can be governed or utilized after leaving the machine. We have built compressors for Compression can be carried, if desired, to the point of liquefaction when proper cooling is provided. Catalogues furnished to business men and engineers upon application. The Norwalk Iron Works Co., SOUTH NORWALK, CONN. The Hendey-Norton Lathe is a Modern Lathe and has no Equal. Its Special Conveniences have each a particular Value and Merit. It is equally valuable in the Laboratory, the Tool Room or General Machine Shop. The Automatic Stop, Reverse in Apron, and Device for Feeds and Screw Cutting make it the most Complete Lathe in use. THE HENDEY MACHINE CO., Torrington, Conn. CAMBRIDGE, MASS. JOURNAL The Franklin Institute is not responsible for the statements and opinions advanced by contributors to the Journal. THE FRANKLIN INSTITUTE Stated Meeting, Held Wednesday, February 15, 1905. The Torresdale Conduit.* BY JOHN W. HILL, Chief Engineer, Bureau of Filtration, Philadelphia. The Torresdale Conduit, constituting, as it does, one of the important elements of the greatfiltration system for the improvement of the water supply of Philadelphia, would, on account of its magnitude aloue, command the interest of engineers. It has, however, been made the subject some criticism. In this paper, the author, who was Chief Engineer in charge of its construction, presents, with ample illustrations, a complete history of the work of construction, the sub-sequent examination, and present condition of the work.-[THE EDITOR.] The Torresdale Conduit, Contract No. 14, Improvement, Ex-tension and Filtration of the Water Supply of Philadelphia, is a large inverted syphon intended to conduct the filtered water from the clear water basin at Torresdale to the pumping station. at Lardner's Point. Its nominal capacity is 300,000,000 gallons per day of twenty-four hours, with a loss of head between *A paper read before the Engineers' Club of Philadelphia, and repeated by request before the Institute. VOL. CLIX. No. 952 16 end shafts of 8.6 feet, and a mean velocity of flow of 5.276 feet per second. Influent Shaft No. 1, is located 1,525.5 feet south of the center line of Pennypack street, at the Torresdale Filters, and from this point the conduit proceeds upon city property, under Pennypack Creek, and through the House of Correction grounds to Holmesburg Avenue; thence south on Eugene Street, as laid down on the City plan, to its intersection with Delaware Avenue; thence south on Delaware Avenue to Effluent Shaft No. 11, at Lardner's Point Pumping Station. The nine intermediate working shafts were distributed along the line of work at locations about 1,400 feet apart, making thus the average length of heading about 700 feet. The depth of Shaft No. 1, at the Torresdale end of the Conduit, measured from the finished head, is 127.39 feet, and of Shaft No. II, at Lardner's Point, from same point of measurement, 117.05 feet. The length of tunnel between end shafts is 13,809.2 feet, and total length of water flow from the center of influent legs at Shaft No. 1 to the center of effluent legs at Shaft No. 11, about 13,968.5 feet. The diameter of Shaft No. I of the tunnel and the lower 68.1 feet of Shaft No. II is uniformly ten feet seven inches on the neat lines of brickwork. The upper 48.9 feet of Shaft No. II is twenty-one feet one inch diameter. The general depth of the center line of tunnel is about 100 feet below ground level. The filtered water is drawn from the clear water basin at Torresdale to Shaft No. 1 through a concrete metal reinforced conduit of horseshoe section, equivalent in area to a circle 10 feet in diameter, 855 feet long from the outlet of the clear water basin to the shaft. This conduit is connected with the shaft at elevation 186.50 T. D. center line, through two cast-iron nozzles bolted to the steel shell of the shaft, one eight feet diameter, and the other seven feet diameter, the direct connection to the conduit being made through the larger nozzle. Each of the nozzles is connected with the conduit and the clear water basin through lengths of riveted steel pipe, twenty-one feet long for the eight foot nozzle, and fourteen feet long for the seven foot nozzle, the steel pipes being enveloped in concrete. The effluent legs at Shaft No. II are respectively fourteen feet and seven feet diameter, of riveted steel, each twenty-eight feet in length, and, like the influent legs at Shaft No. 1, are connected to the steel shell of the shaft with cast-iron nozzles, and rounded mouthpieces. The elevations of the conduit and connections with reference to Torresdale Datum are as follows: Head of Shafts Nos. I and II.. Invert of tunnel at Shaft No. II.. Center line of tunnel at midlength. Invert of 8-ft. connection at Shaft No. I. Floor clear water basin, Torresdale.. High water line, clear water basin, Torresdale. .216.46 89.07 99.41 99.49 .182.50 .182.50 .178.00 .178.00 .192.00 .207.00 181.50 [Torresdale Datum is 200 feet below City Datum, or 200 feet below mean high water in the Delaware River, Philadelphia.] Down to the rock, and for a short distance into it, until the shells were sealed, the permanent and working shafts were made of steel plate lined with brick. Below the rock the permanent shafts are lined with brick backed with concrete. The working shafts were not thus lined, but the rock left in the condition found after blasting. The bends at the bottom of the shaft are entirely of concrete, built to forms ten feet seven inches diameter, on a radius of center line of fifteen feet nine inches diameter, finished with a granolithic surface one inch thick. The tunnel is lined with hardburned brick backed with concrete. The lining of invert is everywhere of two courses of brick, laid to templets on a cradle of concrete. The arch ring varies from three to five courses of brick, depending upon the nature of the material in the roof of the tunnel, above which concrete was packed up to the rock, and where, for lack of space above the arch ring, concrete could not be placed, the voids were filled with Portland cement grout pumped in under about eighty-five pounds pressure per square inch. The grout was usually pumped through the weeper pipes set in the brick masonry to lead the water from back of the arch to the interior of the tunnel or shaft. Considering the carrying capacity of 300,000,000 gallons per day, the velocity at different points between the clear water |