PREFACE. 
In the year Ig09 an appendix to the annual report of 
the King Institute of Madras was published by myself and my 
assistant. This work described the commencement of our 
study on the bacteriology of drinking water-supplies in Madras 
and contained great deal of extremely interesting material 
collected over a period of about 12 months. Had it not 
been for the fact that my stay in Madras was rapidly drawing 
to a close, these results would certainly not have been published 
at the time they were; another year’s work would have 
greatly increased the value of the report. The study of the 
bacteriology of drinking water has been continued both of 
the King Institute in Madras and in my own laboratory in 
Bengal for a period of about 4 years. Hence it appeared to 
us desirable to re-write the Madras report and to bring it up 
to date in the light of the experience gained recently. 
As my assistants (Assistant-Surgeon T. Seethapathy 
Aiyar, L. Mm. & s.,and V. Govindaraju Mudaliyar, B.A.) parti- 
cipated in the original report, they must be mentioned as co- 
workers in this small book. The latter of these gentlemen 
has subsequently come as my Head Assistant in my labora- 
tory in Bengal and is largely responsible for the results reported 
in this book. 
