OF ATMOSPHERIC CHANGES UPON DISEASE. 181 



fall occurs, and it may be noticed that in the two preceding 

 weeks there has also been a slight fall in the degree of 

 humidity, and in the week ending October xoth there is 

 a great diminution of atmospheric pressure (barometer 

 29*4™s, the lowest this year), and this is at once followed 

 by a further rise in the degree of humidity and the num- 

 ber of cases. 



From October lotJi until November list, both the 

 curves remain high, but in their secondary undulations, 

 instead of being in accord, they supplement one another. 



In the week ending November 14/A, the highest degree 

 of humidity accompanies a decline in the disease curve, 

 but is followed in the week after by an increase in the 

 number of cases. The two curves then decline on the 

 whole until December gth, when the returns of disease are 

 discontinued for six weeks. 



In the spring of 1858 the degree of humidity remains 

 tolerably high, without any great prevalence of the disease ; 

 but here again may be noticed for twelve weeks an almost 

 exact accord between the rise and fall of the secondary 

 waves of the two curves. There are two exceptions to this 

 rule : First, in the week ending March 6, the number of 

 cases continues to fall after the sudden depression of the 

 degree of humidity has ceased. In this week the atmo- 

 spheric pressure is again very small (29"6™^), and the week 

 following there is again a sudden rise in both the disease 

 and the humidity curve. 



In the week ending March 9.0th there is no material 

 change in the degree of humidity, but the mean tempera- 

 ture rises 13°, and is 6° above the average, and the scarla- 

 tina-curve descends again. 



During April the number of cases diminishes gradually, 

 and on the whole the humidity- curve declines, but fluc- 

 tuates remarkably, the scarlatina-curve marking these fluc- 

 tuations by slighter variations in accordance with them. 



