FEVERS. 555 



have delivered, the variety of these epidemics is not nearly so 

 great, and we may determine nearly to what length the variety 

 proceeds, reduce them to certain genera, and thereby attain a 

 general method of cure. 



" Now, to do this, we must again consider epidemic diseases 

 more generally, and also the causes which can produce them. 

 Epidemics or diseases affecting a great number of persons at 

 the same time, must arise from certain causes in common to all 

 these different persons. What variety there may be here, I 

 will not negatively determine, but we must seek for them either 

 in the state of the diet or in the state of the air. 



" The Diet I may discuss very shortly, not however following 

 the many conjectures which have been offered about the quali- 

 ties of certain waters which are common like the air. Much has 

 been said about the qualities of waters producing various epide- 

 mic diseases. I could shew the opinion to be ill-founded, but it 

 would lead me too far from my present subject to insist upon 

 this, more especially as it is not alleged that the waters are the 

 cause of epidemic fevers. We will not, therefore, suppose the 

 cause of epidemic diseases to be in the common drink. But, 

 with regard to our solid food, this may be alleged to be the cause 

 with more foundation. Of this there are two noted cases. 



66 First) TheRaphania, a convulsive disorder which arises from 

 a particular corruption of certain grains, particularly the rye ; 

 but as this does not produce epidemic fever, or at least the fever 

 is only symptomatic, I shall take no farther notice of it here. Be- 

 sides this, I do not know of any remarkable poisonous matter 

 being mixed with our common aliment. So the only other case 

 worthy of our attention here, is, 



" Secondly, That of diseases arising in consequence of great 

 famine. I might have taken notice of this among the remote 

 causes of fever, but it was proper to reserve it to this place, for 

 we have no particular species of diseases arising from famines ; 

 and it is pretty obvious that on such occasions a variety of 

 causes act, some of which may produce particular diseases : 

 but the most part of these causes are such as only favour the 

 production, operation, and propagation of miasma and con- 

 tagion, and so give no particular diseases, but only have a spe- 



