144 PRACTICE OF PHYSIC. 



BOOK III. EXANTHEMATA, OR ERUPTIVE 

 FEVERS. 



DLXXXV. The diseases comprehended under this title, which 

 make the .third Order of Pyrexise in our Nosology, are in gene- 

 ral such as do not arise but upon occasion of a specific conta- 

 gion applied, which first produces fever, and afterwards an 

 eruption upon the surface of the body ; and which diseases, for 

 the most part, affect persons but once in the course of their 

 lives. 



DLXXXVI. Whether the character of the order may be 

 thus limited, or if the order may be allowed to comprehend also 

 the eruptive fevers produced by a matter generated in the 

 body itself, and likewise those cases of eruption which do not 

 depend upon contagion, or upon a matter generated before the 

 fever, but upon a matter generated in the course of the fever, 

 I am not ready to determine. Of the diseases enumerated by 

 the Nosologists, as Exanthemata, there are certainly three dif- 

 ferent kinds, which may be distinguished by the circumstances 

 mentioned in this and the preceding paragraph. Of the first 

 kind are the Smallpox, the Chickenpox, the Measles, the 

 Scarlet Fever, and the Plague. Of the second kind seems to be 

 the Erysipelas ; and of the third kind I judge the Miliaria and 

 Petechia to be. But as I am not sufficiently confident in the 

 facts which should support these distinctions, or which would 

 enable us to apply them in all cases, I go on in this book 

 to treat of almost all the Exanthemata enumerated by pre- 

 ceding Nosologists, with only some difference in the arrange- 

 ment from what it was in my former editions. 



" I must here observe, that I find many difficulties in Noso- 

 logy, and nowhere greater than in this place. I am truly not 

 satisfied with this order. This may be considered as an objec- 

 tion to Nosology in general ; but it merely shews that the his- 

 tory of diseases, as it now stands, is far from being complete 

 and accurate ; and I say that it is the attempt at Nosology, 

 which chiefly serves to point out these doubts, to start ques- 



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