ays elapsed between
them, are in very close agreement, and establish the fact that bran is
an accurate medium of measurement.

_Test No 3_.--The 500 ft. of 10-in. pipe in the 16-in. line near the
reservoir (Fig. 2) were replaced by 16-in. pipe in the summer of 1908.

On May 12th, 1909, green aniline was started through the pipe at _A_ at
11.00 A.M., 11.30 A.M., and 12.00 P.M. In each case it appeared at _E_ in
3 hours and 31 min. This time is 20 min. less than that observed in the
tests of the previous year, and is due to the removal of the 10-in. pipe
from the 16-in. line and to the increasing smoothness of the interior
surface of the pipe.

The relative velocities and discharges under the third test, using the
nomenclature of the first and correcting the lengths of pipe on account
of the removal of the 10-in. pipe near the reservoir, are:

48,000 + 12,700
----- --------- = 12,660
_x_ 2.56_x_

_x_ = 4.183

and 2.56_x_ = 10.708

and the discharges are:

From the 10-in. pipe = 5.840 cu. ft. per sec.
" " 16 " " = 5.839 " " " "

_Coefficients_.--On May 12th, 1909, the 10-in. line was working on a
grade of 0.03338, and, with _n_ = 0.009, _C_ should have been 131. It
was actually 138, making _n_ = 0.00866. The 16-in. line was working on a
grade of 0.0030625, and, with _n_ = 0.009, _C_ should have been 145. It
was actually 141, making _n_ = 0.0092.

Referring to the estimated hydraulic grade between Coyote and Corona
(Plate V), the coefficients, 0.01 and 0.012, were used for wood and
iron, respectively, on which basis, the maximum pressure at Coyote was
expected to be 304 lb. and, at Luna, 310 lb. per sq. in. The actual
maximum at Coyote, with pumps at full normal speed, was 270 lb., and, at
Luna, 278 lb., indicating that the values of the coefficients taken were
too high. This checks with the tests between Bonito and Nogal.

Of course, the iron pipe will increase in roughness, and, in time the
pumping pressure will approach the calculated amount. The interior of
the iron pipe now has a smooth coat of asphalt.

_Pipe Breakage_.--The breakage or damage to the wood pipe in shipment
occurred on the ends, the tenons being most exposed to injury from
shifting in the cars. The damage due to the shipment and handling of the
Elmira pipe was 1% and one-half as much for the Bay City pipe. Less than
6 pieces out of 100,000 laid have had to be removed