SCP. I. 17. THEORY OP FEVER. 511 



On this circumstance depends the power of the bitter medi- 

 cines, as the bark, and other stimulating materials, as beer and 

 wine, in preventing the returns of the cold paroxysms of fevers^ 

 and in strengthening the system, which increase of irritability, 

 that is, of strength, continues after the use of the medicine is with- 

 drawn. 



But, on the contrary, if the stimulating material be continued 

 much longer than one lunation, the whole system, or the stimulated 

 organ alone, is excited into too forcible action by the two senso- 

 rial powers of irritation, and of association; and, consequently, in 

 process of time, loses, in some degree, both its irritability and its 

 associability; and inactivity or torpor succeeds; which constitutes 

 weakness, as is seen in all those who accustom themselves to 

 dram-drinking. 



Hence wine or opium, or Peruvian bark, may be continued 

 twice or four times a day for half a lunation, or for a whole one 

 with advantage, in diseases of debility, for the purpose of gaining 

 both diurnal and monthly associations of activity. But should 

 not be much longer continued; as a consequent debility will then 

 be liable to succeed. 



XVII. Conclusion. 



Thus have I given an outline of what may be termed the sym- 

 pathetic theory of fevers, to distinguish it from the mechanic 

 theory of Boerhaave, the spasmodic theory of Hoffman and of 

 Cullen, and the putrid theory of Pringle. What I have thus de- 

 livered, I beg to be considered rather as observations and conjec- 

 tures, than as things explained and demonstrated; to be considered 

 as a foundation and a scaffolding, which may enable future indus- 

 try to erect a solid and a beautiful edifice, eminent both for its 

 simplicity and utility, as well as for the permanency of its mate- 

 rials, which may not moulder, like the structures already erect- 

 ed, into the sand of which they were composed; but which may 

 stand unimpaired, like the Newtonian philosophy, a rock amid 

 the waste of ages! 



END OF THE SECOND PART. 



