THE FLOW OF WATEB IN" CONCRETE PIPE. 89 



No. 63, Experiment F-S. — Sudbury Aqueduct, Metropolitan water 

 works, Boston, Mass. — Alphonse Fteley and F. P. Stearns conducted 

 a series of experiments upon the Sudbury Aqueduct in 1880. 1 The 

 conduit was new, of horseshoe shape, 9 feet wide and 7.7 feet high. 

 The discharge was measured over a weir. This aqueduct contained 

 sections lined with brick alone, and also sections lined with a coating of 

 cement mortar over the brick. After stating that the capacity of 

 the brick section is represented by the formula V=l27R°- 6 's - 5 , they 

 add: 



When the inside of the conduit is lined with a coating of mortar made of fine Port- 

 land cement, its flowing capacity is from 7 to 8 per cent greater. This coating, though 

 applied with floats, did not present as smooth a surface as was obtained in other por- 

 tions of the conduit, where experiments would probably have given higher results. 

 In some parts of the conduit where the brick surface was covered with a wash of Port- 

 land cement laid with a brush, the flowing capacity was increased to the extent of 

 from 1 to 3 per cent. 



Note that the exponents in the above formula are the same as those 

 adopted by the writer. Also see discussion by Mr. Hazen on page 97. 

 For the cement-lined section their formula would have read F=137 

 R°- 62 s - 5 , which becomes, in terms used by the writer (see p. 49), 

 F=0.394(i - 62 J? - 5 , indicating a capacity about 6 per cent greater 

 than the formula for the best grade of construction as suggested by 

 the writer. 



Nos. 65, 66, and 67, Experiment H. — 108-inch cement-washed 

 brick sewer, North Metropolitan sewerage system, Boston, Mass. 2 — 

 Theodore Horton describes experiments conducted upon a 9-foot 

 circular brick sewer, the interior of which had been washed with 

 cement mortar. So far as carrying capacity is concerned, the pipe is 

 of cement. Extending over a period of several years, these tests show 

 what may be expected with the lapse of time, when sewage is con- 

 veyed in a concrete or cement lined channel. Below the East Boston 

 pumping station the cross section of the sewer is a 9-foot circle for 

 2,000 feet; thence a horseshoe shape of the same area as the circle 

 for 2,000 feet; thence another 9-foot circle for an additional 3,000 

 feet. A uniform gradient of 1 foot fall in 3,000 feet is maintained. 

 The exact length of reach tested is not disclosed, but the statement 

 is made that simultaneous measurements of depth showed the flow 

 line above the horseshoe cross section to be parallel to the invert. 

 Thus the nominal grade of the line might be accepted without correc- 

 tion for any change in the velocity due to nonparallel flow. The 

 discharge was determined with carefully conducted current-meter 

 gaugings and the cross section by actual measurement. The first 

 series was made in 1896, 10 months after the system at this point 

 had been put in operation. The next series was made in 1897, after 

 these channels had been in operation about 26 months, during which 

 time ample opportunities for changes in the carrying capacity had 

 taken place. 



The third series was made in 1900. The sides of the sewer, above 

 and below the average water line, were covered with a thin coating 

 of grease of a leaden color, and supported an organic growth, prob- 

 ably of a fungus nature. By this time there were slight incrusta- 

 tions at frequent intervals, due to barely visible seepage of ground 

 water, and the growth, while not much heavier, covered a greater 



1 Trans. Amer. Soc. Civil. Engin. vol. 12, p. 17. See also Jour. Assoc. Eng. Soes. vol. 26, p. 163. 

 « Trans. Amer. Soc. Civ. Eng., 46 (1901), p. 78. 



