o the turbidity in the applied water, it follows that an
applied water of given turbidity will produce an effluent at 35 deg.
with a turbidity twice as great as at 75 degrees. This is quite in
accordance with the facts obtained in actual operation, as indicated
on the diagram, Figure 15.

_Preliminary Treatment of the Water._--The most striking features of
the bacterial results given in Table 4 are, first, the uniformly low
numbers of bacteria in the filtered water during perhaps 8 or 9
months of the year, and the increase in numbers each winter. This is
shown clearly in the analysis of bacterial counts in Table 32.

~Table 32--Classification of Daily Bacterial Counts in
the Filtered-Water Reservoir During the Period,
November 1st, 1905, to February 1st, 1908.~
==========================+==============+======================
Bacterial count between: | No. of days. | Percentage of whole.
--------------------------+--------------+----------------------
0 and 20 per cu. cm. | 291 | 41.0
20 and 40 per " " | 245 | 34.6
40 and 60 per " " | 63 | 8.9
60 and 80 per " " | 30 | 4.2
80 and 100 per " " | 28 | 4.0 92.7
--------------------------+--------------+----------------------
100 and 200 per " " | 29 | 4.1
200 and 300 per " " | 13 | 1.8
300 and 500 per " " | 5 | 0.7
500 and 1000 per " " | 5 | 0.7 7.3
--------------------------+--------------+----------------------
| | 100.0
==========================+==============+======================

The tests for _Bacillus Coli_ in Table 5 show results which
correspond closely to these, with this organism detected only
infrequently, except during the periods of high bacteria, and both
of these are parallel to the turbidity variations in the filtered
water. These variations follow closely the variations in the
turbidity and in the bacterial content of the water applied to the
filters.

By all standards of excellence, the sanitary quality of the water
during the greater part of the time is beyond criticism. In view of
the close parallelism of turbidity and bacterial results in the
applied and in the filtered water, it is entirely logical to
conclude that, if the quality of the applied