THE FLOW OF WATER 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 1S80. 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= 127R°- 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 7=137 
R°- e2 s - 5 , which becomes, in terms used by the writer (see p. 49), 
F=0.394^°- 62 i7 - 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 
P 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 
I taken place. 
f 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. Socs. vol. 26, p. 163. 
2 Trans. Amer. Soc. Civ. Eng., 46 (1901), p. 78. 
