80 BULLETIN 85a, TJ. S. DEPARTMENT OF AGKICULTURE. 



columns in graduated glass tubes, installed at each end of the reach 

 tested. The relative elevations of these gauges were established by 

 the static head; that is, with still water in the line. The piezometer 

 connections were of type D (fig. 3), different from anything used in 

 American experiments, so far as the writer is informed. A perforated 

 brass ball, 30 millimeters in diameter, was set at the center of the 

 pipe. In order to annul all influence of velocity head and secure 

 only pressure head, the balls were filled with brass shavings. The 

 usual tubing connection is made between the balls and the gauge 

 glasses, through stuffing boxes set in the shell of the pipe. 



The volume of water was measured over a specially formed weir, 

 having end contractions. 



Piezometer No. 1 was located about 1£ diameters from the intake 

 of the pipe line. This would appear to be at a point subject to much 

 disturbance. The weir is located about 8 or 10 feet below the power 

 house and no mention is made of baffles to still the velocity of 

 approach. These conditions may offer grounds for criticism of this 

 series, although the platted points appear to be consistent with the 

 exception of observation No. 3, which was excluded by the writer in 

 consideration of this series, as there is probably some error of obser- 

 vation or typography. 



No. 38, Experiment M-l. — 110-inch siphons, Catskill Aqueduct, 

 New York. — The Catskill Aqueduct contains several pipe siphons 

 using identical construction for inlet and outlet chambers and for the 

 siphon proper. The latter is in essentials a steel pipe, fined with 2 

 inches of cement mortar and protected outside with at least 6 inches of 

 concrete. 1 



One siphon was lined with a cement-gun process while the others 

 were grouted. For both processes, the invert, for a width of about 8 

 feet of arc, was lined in the manner employed in laying sidewalks. 

 When the cement gun was used the coat was applied in layers in 

 rapid succession. Each layer is sufficiently rough for a secure bond 

 with the next one. The resulting surface was floated and troweled 

 to secure a smooth finish. The cement-gun process was abandoned 

 by the contractor after one siphon had been so lined. In the grouting 

 method, metal-covered wood forms were used after extensive experi- 

 mentation. The grout was placed through a 2i-inch pouring pipe 

 inserted in a rivet-passing hole and subjected to a head of about 4 feet 

 above the zenith of the pipe. The first batch or two of grout for each 

 set-up, 15 feet in length, was mixed 1 part cement to 1 of sand) while 

 the succeeding batches were mixed in a ratio of 1 to 2. By both 

 processes "very smooth interior surfaces were secured. " (See p. 82.) 



In Table 3 are shown average coefficients for observations on the 

 Esopus, Tongore, Foundry Brook, Sprout Brook, Peeksill, Hunters 

 Brook, Turkey Mountain, and Harlem Railroad siphons, for a flow 

 of 350 million gallons per day (542 second-feet). Concerning these 

 observations, made in August of 1915 under the direction of Mr. 

 F. F. Moore, the board of water supply writes : 



The condition was not favorable for obtaining the best results on the pipe siphons. 

 * * * The result of measurements of flow in pipe siphons was recorded as an 



lEngin. Rec., vol. 63, Apr. 15, 1911, p. 404; id., vol. 64, Sept. 16, 1911, p. 332; Eng. News, vol. 66, p. 526; 

 Municipal Jour, and Engineer., Vol. 31, Aug. 23, Mill, p. 229: id., Dec. 7, vol. 31, 1911, p. 719: Jour. N. E. 

 Water-Wks. Assn., Sept.,1911: Waterworks Handbook, by Flynn, Weston, and Bogert, New York, 1916, 

 p. 323. 



