630 PHILOSOPHICAL TRANSACTIONS. [aNNO 1780. 



their base. The face had the greatest number ; and these were in general the 

 most indistinct. They were somewhat flattened with a dent in the middle.* 



So far were the leading circumstances and external appearances in favour of 

 their being the variolous eruption ; but though these leading circumstances and 

 external appearances were incontrovertible, yet they were not an absolute proof 

 of this being the genuine small-pox ; therefore I must be allowed to consider 

 this subject a little further, and see how far all the circumstances correspond, or 

 are similar to the true small pox. In the small-pox we have a previous fever, in- 

 stead of which, in the present case, we have no information but that of the 

 mother having had the small-pox within such a limited time as may favour the 

 possibility of infection in the womb ; yet we may presume, that the child must 

 have had considerable fever preceding such an eruption, of whatever kind it was. 



In the small pox the eruption goes through pretty regular stages in its pro- 

 gress and declension, which circumstances we know nothing of in the present 

 case ; but even this fever, the eruptions, and their progress, are not absolutely 

 proofs that the disorder is the small-pox when it is caught in the common and 

 natural way : and in proof of this assertion it may be observed, that practi- 

 tioners every now and then are mistaken. 



It may be asked, what is the true characteristic of the small-pox ? That by 

 which it differs from all other eruptions that we are acquainted with ? The most 

 certain character of the small-pox, that I know, is the formation of a slough, 

 or a part becoming dead by the variolous inflammation ; a circumstance which 

 hitherto, I believe, has not been taken notice of. This was very evident in the 

 arms of those who were inoculated in the old way, where the wounds were con- 

 siderable, and were dressed every day ; which mode of treatment kept them 

 from scabbing, by which means this process was easily observed ; but in the pre- 

 sent method of inoculation it is hardly observable : the sore being allowed to 

 scab, the slough and scab unite and drop off together. The same indistinctness 

 attends the eruptions on the skin ; and in those patients who die of, or die 

 while in, the disease, where we have an opportunity of examining them while 

 the part is distinct, this slough is very evident. This slough is the cause of the 

 pit after all is cicatrized ; for it is a real loss of substance of the surface of the 

 cutis : and in proportion to this slough is the remaining depression. 



The chicken-pox comes the nearest in external appearance to the small-pox ; 

 but it does not commonly produce a slough. As there is generally no loss of 

 substance in this case, there can be no pit. But it sometimes happens, though 



* I endeavoured to take some matter upon the point of 2 lancets 5 but not having an opportunity 

 of making an experiment myself, I gave them to two gentlemen, who, I imagine, were afraid of 

 inoculating witli them. — Orig. 



