OF ATMOSPHERIC CHANGES UPON DISEASE. 175 



As thougli the lieat liad called into activity some agent 

 which resisted moderate fall of temperature, but which 

 was destroyed by the cold of November, December, and 

 January.* 



During the whole time of the gradual increase of the 

 disease the mean temperature is throughout above the 

 average. 



From February 1858 the fever curve does not rise much 

 until the week ending June ^/A, when a sudden increase 

 of 1 10 in the number of cases accompanies a rise of 12° in 

 the mean temperature. 



From April nth 1858 to October o.'^rd, there is the 

 same gradual advance in the disease curve as in the corre- 

 sponding period of 18^7, with the exception of the month 

 of June 1858. The temperature this month was excessive, 

 and to this in a great measure must be attributed the 

 sudden rise in the number of cases. The month of July, 

 which followed, had a temperature considerably below the 

 average, and this checked the rapid advance of the disease 

 for a time ; but it will be seen that leaving the month of 

 June out of the question (as being abnormal) the curve 

 gradually ascends up to October 2'^rd, when our observa- 

 tions end. 



Of the lesser modulations of the fever curve 61 per cent 

 take place in accordance with the variations of the mean 

 temperature, the disease rising and falling with the tem- 

 perature; and in many of those weeks which present 

 deviations these seem to be due to the lagging of the 

 disease curve behind that of temperature ; as in the weeks 

 April 18, 25, May 2, June 6, 13, August 15, 22, 29, and 

 September 5 and 25, 1857; also March 27, May 1, June 

 26, September 4, 11, i858.t 



* Drs. Donnelly and Wilde remark that fever, although, very prevalent 

 in spring, seldom rises to its intensity until summer and autumn. 



t It takes birth when spring passes into summer, and it rises towards 



