170 MESSRS. RANSOME AND VERNON ON THE INFLUENCE 



on which the disease took its first decided rise in the pre- 

 ceding year). The mean temperature has now been very- 

 high for a fortnight (from 8° to 10° above the average); 

 and the number of cases rapidly increases until July 10th, 

 when it may be noticed that the mean temperature falls 

 suddenly to 56° (6° below the average), and the further 

 progress of the disease is checked. 



After a short rise on July 2^th (the mean temperature 

 having then again risen 5° above the average for the week) 

 the dysentery curve now gradually subsides, with many 

 fluctuations, until October 2nd; and it may be noticed 

 that the most decided rise is in the week ending Septem- 

 ber 25/A, following the unusually high temperature of the 

 preceding week (64° or 6'^° above the average).* 



Pneumonia 



Seems to be very greatly influenced by the mean tempe- 

 rature, the disease curve rising as the temperature 

 falls, and vice versa. 



The above statement receives its best illustration in the 

 spring, summer, and autumn of the year 1857. 



In the early- part of the year, while the temperature 

 remains low, the disease is still prevalent, but as the 



* Hippocrates, Aph. 22, book iii., speaks of dysentery as an autumnal 

 disease : " With regard to the seasons, if winter be of a dry and northerly 

 character, and the spring rainy, and southerly, in summer there wiU neces- 

 sarily be acute fevers, opthalmies, and dysenteries, especially in women, and 

 in men of humid temperament." — Aph. 3, xi. 



Sydenham mentions dysentery, amongst other diseases, "which com- 

 mencing in August run on to winter." 



In the report upon the status of disease, drawn from returns made at the 

 time of the census of Ireland for the year 1851, Messrs. Donnelly and 

 Wilde conclude that diarrhoea and dysentery prevail more in the summer 

 and autumn than at any other season. 



" They occur in the season of summer ; next in autumn ; less in spring ; 

 least of all in winter." — Aretseus, On the Causes and Symptoms of Chronic 

 Diseases, book ii. ch. ix. 



