be excessive, a careful examination of the course of the sewers
should be made with a view to locating the places where the
greater part of the leakage occurs, and then to take such steps
as may be practicable to reduce the quantity.




CHAPTER VI.

GAUGING FLOW IN SEWERS.


A method frequently adopted to gauge the flow of the sewage is
to fix a weir board with a single rectangular notch across the
sewer in a convenient manhole, which will pond up the sewage;
and then to ascertain the depth of water passing over the notch
by measurements from the surface of the water to a peg fixed
level with the bottom of the notch and at a distance of two or
three feet away on the upstream side. The extreme variation in
the flow of the sewage is so great, however, that if the notch
is of a convenient width to take the maximum flow, the hourly
variation at the time of minimum flow will affect the depth of
the sewage on the notch to such a small extent that difficulty
may be experienced in taking the readings with sufficient
accuracy to show such variations in the flow, and there will be
great probability of incorrect results being obtained by reason
of solid sewage matter lodging on the notch. When the depth on
a l2 in notch is about 6 in, a variation of only 1-16th inch in
the vertical measurement will represent a difference in the