VACCINATION AGAINST SMALLPOX 221 



of noticing the effects of a singular disease, and of view- 

 ing the progress of the most curious experiment that ever 

 was recorded in the history of physiology. 



"I remain, dear sir, etc., 



" JOSEPH H. MARSHALL." 



"P.S. I should have observed that, of the patients I 

 inoculated and enumerated in my letter, one hundred and 

 twenty-seven were infected with the matter you sent me 

 from the London cow. I discovered no dissimilarity of 

 symptoms in these cases from those which I inoculated from 

 matter procured in this country. No pustules have occurred, 

 except in one or two cases, where a single one appeared 

 on the inoculated arm. No difference was apparent in the 

 local inflammation. There was no suspension of ordinary 

 employment among the labouring people, nor was any 

 medicine required. 



" I have frequently inoculated one or two in a family, 

 and the remaining part of it some weeks afterwards. The 

 uninfected have slept with the infected during the whole 

 course of the disease without being affected; so that I 

 am fully convinced that the disease cannot be taken but 

 by actual contact with the matter. 



" A curious fact has lately fallen under my observa- 

 tion, on which I leave you to comment. 



" I visited a patient with the confluent smallpox and 

 charged a lancet with some of the matter. Two days 

 afterwards I was desired to inoculate a woman and four 

 children with the cow-pox, and I inadvertently took the 

 vaccine matter on the same lancet which was before charged 

 with that of smallpox. In three days I discovered the mis- 

 take, and fully expected that my five patients would be 

 infected with smallpox; but I was agreeably surprised to 

 find the disease to be genuine cow-pox, which proceeded 

 without deviating in any particular from my former cases. 

 I afterwards inoculated these patients with variolous matter, 

 but all of them resisted its action. 



" I omitted mentioning another great advantage that now 

 occurs to me in the inoculated cow-pox; I mean the safety 

 with which pregnant women may have the disease com- 



