OF ATMOSPHERIC CHANGES UPON DISEASE. 171 



warm weather advances it gradually declines, and remains 

 low tlirougliout the unusually warm summer, being least 

 prevalent when the mean temperature is highest in July 

 and August. The number of cases begins to rise in the 

 latter end of August, and reaches its maximum on Novem- 

 ber 28/A, the mean temperature being then 42°. 



During this period, the way in which the two curves of 

 mean temperature and pneumonia supplement one another 

 is very remarkable. From April 11th to November 2^th 

 (thirty-four weeks) there are only seven exceptions to this 

 rule, and when we examine these we find that most of 

 them may be accounted for without much difficulty. 



The first of the exceptions occurs in the week ending 

 May gth, when the disease curve rises considerably, the 

 temperature also rising, but it must be remarked that the 

 temperature is still 7° below the average, and that in the 

 preceding week it was y^° below the average. ' 



In the week ending May 2.'^rd another, but very slight, 

 deviation from our rule may be noticed, — the pneumonia 

 curve continues to descend, while there is a slight fall 

 (half a degree) in the temperature. 



In the week ending June 20th there is a temporary rise 

 in the number of cases, together with the mean tempera- 

 ture, but this seems again to be accounted for by the 

 occurrence of a temperature 2° below the average in the 

 preceding week. 



In the week ending August 29/^ there is a slight rise 

 in the number of cases, which cannot be accounted for by 

 any fall of the mean temperature (68° or 9° above the 

 average). (The N.E. winds prevailed this week, fol- 

 lowing a long continuance of S.W. winds, and the 

 degree of humidity rapidly fell.) 



In the week ending September 26th the number of cases 

 diminishes during a falling temperature, but in the pre- 

 ceding week the mean temperature was 5 •5° above the 



