THE WATER SUPPLY OF LONDON. 



179 



about nine inches below the surface of the water in partially 

 exhausted and sealed tubes, the ends of which, when the 

 tubes were lowered to the required depth, were broken off 

 by an ingenious contrivance devised by my Assistant, Mr. 

 Burgess. On being withdrawn from the river the tubes 

 were immediately hermetically sealed and packed in ice for 

 conveyance to my laboratory, where the cultivation was 

 always commenced within four hours of the time of collection. 



No. 8. 



For the records of sunshine, I am indebted to the 

 kindness of Mr. James B. Jordan of Staines ; and for 

 gaugings of the Thames at Teddington Weir to Mr. C. J. 

 More, the engineer to the Thames Conservancy Board. 



The graphic representation of these collateral observa- 

 tions affords definite evidence as to which of the three 

 conditions — temperature, sunshine, and Mow of the river — 

 has the predominant influence upon bacterial life in the 

 water. The first diagram (No. 7) compares the number of 



13 



