2 38 



Cholera in Relation to Certain Physical Phenomena, [part i. 



TABLE XXXVIII. 



Average ^physical characters of the three seasons of Cholera-jpievalence, June and 

 October being excluded from the months of medium 'prevalence. 



Meteorologicai, conditions. 



Atmospheric Pressure ... 

 „ Temperature 



„ Humidity 



Eainfall ... 



Water-level 



Temperature of the soil 



Carbonic acid in the soil-air 



Seasons or prevalence. 



Medium. 



30-007 

 70°-2F. 

 69 

 0"-44 

 13' -1" 

 75°-3F. 

 5 



Maximum. 



29-806 

 81°-1 

 70 

 2"-51 

 14' -4" 

 77°-0 

 1 



Minimum. 



29-614 

 83°-3 

 87 



12"-17 



10' -0" 



81°-8 



4 



The season of minimum prevalence is, according to these data, characterised by 

 low atmospheric pressure, high atmospheric and soil temperatures, by extreme atmo- 

 spheric humidity and rainfall, by elevation of the water-level, and by obstructed 

 ventilation of the soil as indicated by the amount of carbonic acid in the soil-air. The 

 season of medium prevalence is characterised by high atmospheric pressure, low at- 

 mospheric and soil-temperature, by minimum humidity and rainfall, by depression of 

 the water-level, and by obstructed ventilation of the soil. The season of maximum 

 prevalence shows characters occupying an intermediate position in regard to those of 

 the other two seasons except in so far as its water-level and soil-ventilation are concerned. 

 The former of these is at a maximum of depression, the latter at a maximum of activity. 

 According to these data, the depression of the water-level and the increase of soil 

 ventilation are the only phenomena which reach a climax during the season of maximum 

 prevalence of cholera. 



When June and October are included with the other months of medium prevalence 

 the results of the comparison are slightly modified. 



TABLE XXXIX. 



Average characters of the seasons of Medium, Maximum and Minimum prevalence, 



of Cholera. 



