244 THE CHEMISTRY OF CREATION. 



lebone, Pancras, Islington, Hackney, and Hamp- 

 stead all more or less elevated the deaths from 

 this disease amounted only to seven-. 



The Thames presents the large evaporating 

 surface to the inhabitants of London of about 

 2,245 acres. Mr. Glaisher calculates that each 

 acre evaporates 1,857 '6 gallons daily; conse- 

 quently, 4,170,000 gallons are raised from this 

 part of the Thames on an average daily through- 

 out the year! Thus about 18,000 tons of water 

 are daily thrown into the atmosphere of London, 

 and become intimately mixed therewith. The 

 contents of sinks and drains are disgorged by 

 the great sewers into the waters, and are 

 agitated with the mud, from which vapours are 

 constantly given off in enormous quantities. 

 .During the prevalence of cholera, the mean 

 night temperature of this river from May 27 to 

 September 15, 1849, was 64! Hence, evapo- 

 ration was largely taking place into the air of 

 the sleeping city. It is a fact well worthy of 

 attention, that after the temperature of the river 

 has risen above 60, diarrhoea and dysentery be- 

 come prevalent, disappearing as the temperature 

 again subsides. This appears to show a con- 

 nexion between the atmospheric moisture and 

 impurities and the prevalence of disease, in a 

 very marked manner. 



Cholera has been regarded by some as a 



