SUP. I. 17. THEORY OF FEVER. 511 



On this circumftance depends the power of the bitter medi- 

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

 wine, in preventing the returns of the cold paroxyfmsof fevers, 

 and in flrengthening the fyftem, which increafe of irritability, 

 that is of ftrength, continues after the ufe of the medicine is 

 withdrawn. 



But on the contrary, if the ftimulating material be continued 

 much longer than one lunation, the whole fyftem, or the ftimu- 

 lated organ alone, is excited into too forcible aclion by the two 

 fenforial powers of irritation, and of aflbciation*; and confe- 

 quently in procefs of time lofes in fome degree both its irrita- 

 bility and its aflbciability ; and inactivity or torpor fucceeds ; 

 which conftitutes weaknefs, as is feen in all thofe, who accuf- 

 tom themfelves 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 difeafes of debility, for the purpofe of 

 gaining both diurnal and monthly aflbciations of activity. But 

 ihould not be much longer continued j as a confequent debility 

 will then be liable to fucceed. 



XVII. Conclujton. 



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

 fympathetic theory of fevers, to diftinguifh it from the mechan- 

 ic theory of Boerhaave, the fpafmodic theory of Hoffman and 

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

 thus delivered, I beg to be confrdered rather as obfervations and 

 conjectures, than as things explained and demonitrated ; to be 

 confidered as a foundation and a fcaftbldiag, which may enable 

 future induftry to erect a folid and a beautiful edifice, eminent 

 both for its fimplicity and utility, as well as for the permanency 

 of its materials, which may not moulder, like the ftruclures 

 already erected, into the fand of which they were compofed ; 

 but which may (land unimpaired, like the Newtonian philofo- 

 phy, a rock amid the wafte of ages ! 



END OF THE SECOND PART. 



LINES* 



