As would be expected, the velocity of flow in these pipes may be and generally is considerably higher than the velocity of movement in masonry channels. Both Tables XV and XVI give considerable range of coefficients computed and arranged from authoritative sources, and the coefficients _c_ for Chezy’s formula represent the best hydraulic practice in connection with such works at the present time. In using the formula for any special case, great care must be taken to select a value for _c_ which has been established for conditions as closely as possible to those in question. This is essential in order that the results of estimated discharges may not be disappointing, as they sometimes have been where that condition so necessary to accuracy has not been fulfilled. TABLE XV. VALUES OF COEFFICIENT _c_. LEGEND: (A) = Hydraulic Radius _r_. (B) = Hydraulic Gradient. (C) = Mean Velocity. ------------------------------+-----------------+-----+-------+------ | | | | Pipe-line. | Diameter. | | | | | (A) | (B) | (C) ------------------------------+-----------------+-----+-------+------ Hemlock Lake |36″ wrought-iron | 9″ |.000411| 1.532 ” ” |24″ wr’t and cast| 6″ |.00239 | 3.448 Rush Lake to Mt. Hope |24″ cast-iron | 6″ |.00255 | 3.448 ------------------------------+-----------------+-----+-------+------ Sudbury aqueduct |48″ ” ” | 12″ | | 3.738 ” ” |48″ ” ” | 12″ | | 4.965 ” ” |48″ ” ” | 12″ | | 6.195 ” ” |48″ ” ” | 12″ | | 3.738 ” ” |48″ ” ” | 12″ | | 4.965 ” ” |48″ ” ” | 12″ | | 6.195 ------------------------------+-----------------+-----+-------+------ East Jersey Water Co. |48″ steel riveted| 12″ |.002 | 4.62 | pipe | | | Timber-stave pipe, Ogden, Utah|72″.5 | | | .5 ” ” ” ” ” |72″.5 | | | 1.0 ” ” ” ” ” |72″.5 | | | 1.5 ” ” ” ” ” |72″.5 | | | 2.0 ” ” ” ” ” |72″.5 | | | 2.5 ” ” ” ” ” |72″.5 | | | 3.0 ” ” ” ” ” |72″.5 | | | 3.5 ” ” ” ” ” |72″.5 | | | 4.0 ------------------------------+-----------------+-----+-------+------ LEGEND: (A) = Coefficient _c_.