184 MESSRS. RANSOME AND VERNON ON THE INFLUENCE 



these two elements might act together, the temperature 

 falhng as the degree of humidity and disease-curve rise, 

 and vice versa. Of the weeks in which the degree of 

 humidity and temperature rise and fall together, the appa- 

 rent effects, as shown in the rise and fall of the disease- 

 curve, are almost exactly balanced, there being fifteen 

 points of agreement with the temperature, sixteen with 

 the humidity-curve. The fact of accordance between the 

 rise and fall of the curves, however, must be of little im- 

 portance in determining the influence of the element upon 

 the disease, compared with observations upon the actual 

 state of the air at the time of prevalence or absence of the 

 disease. 



A fcAV instances will, we think, show that the tempera- 

 ture, although by no means inactive, exerts less influence 

 than the humidity. 



While the degree of humidity is at its lowest point in 

 1857, between June 6 and July 18, the number of cases is 

 also the least, scarcely rising above thirty. During the 

 corresponding period in 18^8, between April 1 and July 

 10, although the disease is rather more prevalent than in 

 the year before, yet the number of cases rarely exceeds 

 fifty, and does not increase until the degree of humidity 

 begins on the whole to rise. 



Both in 18^7 and 1858, when the amount of moisture in 

 the air is greatest, the disease-curve is at its highest point. 



On the other hand, a low degree of temperature accom- 

 panies both the smallest and largest number of cases in 

 both 18^7 and 18^8, and the same is true of a high tem- 

 perature; e.g. on July 18, 18^7, the mean temperature is 

 68° while the disease is at twenty-five, and in August 

 18^8, with the mean temperature above 60°, the number 

 of cases remains above 100. Notwithstanding this remark, 

 however, many of our observations will prove that tem- 

 perature has an important modifying action. 



