178 



SCIENCE PROGRESS. 



the temperature of the water was low, and the lowest 

 in summer or when the temperature was high. 



Now, besides temperature, there are two other conditions 

 to either of which this difference may be attributed, viz. y 

 sunshine and rainfall, and I have endeavoured by a series 

 of graphic representations to disentangle these possible 

 influences from each other by placing the results of the 

 microbe determinations in juxtaposition with (i) the tem- 

 perature of the water at the time the samples were taken ; 



No. 7. 



(2) the number of hours of sunshine on the day and up to 

 the hour when each sample was drawn and on the two 

 preceding days, and (3) the flow of the Thames over 

 Teddington Weir on the same day expressed in millions 

 of gallons per twenty-four hours. Although the graphic 

 representations were confined to the Thames, the conditions 

 affecting bacterial life in this river are doubtless equally 

 potent in other rivers and streams. 



The samples for microbe cultivation were collected at 



