9.2 | 261-1/4 | 2,350 | 9.0
November | 54 | 397 | 7.4 | 0 | 0 | ...
December | 62 | 382 | 6.2 | 0 | 0 | ...
---------+-----------+--------+-----------+---------+--------+---------
1910.
---------+-----------+--------+-----------+---------+--------+---------
January | 104 | 703 | 6.8 | 0 | 0 | ...
February | 106-1/2 | 1,058 | 9.9 | 28-1/4 | 371 | 13.1
March | 98 | 985 | 10.0 | 72 | 1,008 | 14.0
April | 268-3/4 | 2,852 | 10.7 | 134-1/4 | 2,159 | 16.1
May | 58-3/4 | 693 | 11.8 | 171-3/4 | 3,042 | 17.7
June | 58-3/4 | 642 | 10.9 | 9-3/4 | 166 | 17.0
=========+===========+========+===========+=========+========+========

The cost for pumping water for sand handling, including all labor,
materials, and repairs, amounts to $0.06 per cu. yd. of sand ejected
and washed, and $0.03 per cu. yd. for replacing.

In addition to the water used for carrying the sand which is being
replaced, it is customary to keep a slight upward flow in the
filter, thus using about 500,000 gal. of filtered water per day for
this purpose. Assuming the value of this water to be the total cost
for pumping, filtering, etc., or $3.80 per 1,000,000 gal., the cost
per cubic yard of sand replaced would be about $0.02 when one
ejector is used, and $0.01 when two are in operation.

It is not considered absolutely necessary to have an upward flow of
water in the filter which is being re-sanded, and it is not always
done. It was used, however, as an additional safeguard against the
formation of a stratum of mud between the old and new layers of sand
while the hydraulic method was in an experimental stage.

The quantities of sand removed from the filters per scraping and the
rates of sand handling are shown in Tables 11 and 12.

_Cost of Operation._--It is frequently difficult to compare the
relative cost of corresponding items for different plants, because
of the different methods of dividing the cost and the varying
opinions of the officials as to what should properly be charged to
each item.

In order that the data may be in sufficient detail to permit it to
be rearranged to compare with other plants, a list of employees and
charges for supplies is given in Table 13. This list accounts for
the entire appropriation for the care a