70 THOMPSON YATES LABORATORIES REPORT 
From these figures it will be seen that the storm water filters produce a 
very considerable bacterial purification. The satisfactory action of these beds is 
probably explained by the very long periods of rest which they obtain. 
Clogging of Filter Beds 
A year's constant working having very considerably reduced the capacity 
of the beds, it has been decided to give them a rest from June 9th, 1900. 
Before doing so, however, analyses were made on June 9th to show exactly the 
bacterial condition of the effluents after the one year's working. The following table 
shows the number of bacteria per c.c, the number of B. coli, and the presence or 
absence of the B. enteritidis sporogenes. It will be seen that the numbers still 
remain very high. 
Source 
Bacteria per c.c. 
B. coli per c.c. 
B. cntcritidis sporogenes .01 c.c. 
Bed la 
1,270,000 
7,000 
Present 
Bed za 
837,000 
2I,IOO 
Absent 
Bed 3^ 
740,000 
12,000 
Present 
