i8o 



SCIENCE PROGRESS. 



microbes per cubic centimetre with the temperature at the 

 time the sample was taken. The horizontal lines express 

 the numbers of microbes and the temperature, while the 

 vertical lines denote the months when the samples were 

 taken. For obvious reasons the horizontal lines express- 

 ing the numbers of microbes and temperatures are num- 

 bered in opposite directions. 



The diagram shows that although coincidences between 

 a high number of microbes and a low temperature are not 



No. 9. 



wanting, some other condition entirely masks the effect, if 

 any, of temperature. 



The next diagram (No. 8) institutes the comparison 

 between the number of microbes and the hours of sun- 

 shine to which the water has been exposed. The diagram 

 is constructed on the same lines as the first. 



It is here seen that, as in the case of temperature, 

 there is some other condition which entirely overbears the 

 influence of sunlight in the destruction of microbes in the 



