Epidemics. 287 



nor too long continued droughts, are admitted as the cause 

 or causes of epidemic disease, in the broad sense of that 

 word ; but something more regular, constant, systematic, 

 and always fraught with marked changes in the form of 

 diseases, and in the type of those diseases, which are of a 

 more constant and ever-present character as inflam- 

 mations and haemorrhages, etc., as contrasted with new 

 forms, like to Black death and cholera. And, with these 

 changes in disease, the intellectual and moral condition 

 of mankind have been closely associated, or at least 

 an attempt has been made to show the probability of 

 such a relationship. 



It is well to remark that mildew, foggy weather, long 

 frosts, long droughts, volcanoes, and earthquakes, and it 

 may be in some very limited manner comets and eclipses, 

 each have some effect in the promotion of epidemics, but 

 that promotion partakes more or less of an " endemic character." 

 In the case of volcanic eruptions and earthquakes, especially 

 in those of the fourteenth and fifteenth centuries, certain 

 emanations of a gaseous or material character may also have 

 partaken of a poisonous character, and, to whatever extent 

 those emanations extended, there specific diseases might 

 have arisen as a direct effect of the diffusion of a poisoned 

 atmosphere ; yet, even under such circumstances, the spread 

 of disease could scarcely be conceded to have much more 

 than a widespread local or endemic influence. But in such 

 a disease as the Levant plague or cholera, the regular 

 advance and encircling diffusion over the globe, in the 

 process of years, could scarcely be allowed to have its origin 

 and diffusion as a sequence and effect of any particular 

 emanation from any particular spot upon the earth's surface. 

 Its march and invasion would forbid any such hypothesis, 

 unless it be admitted that some particular emanation in 

 itself cast out and diffused some special kind of vegetable or 



