220 EDWARD JENNER 



any convenient utensil upon the pustule, suffered to r-- 

 main about forty seconds, and afterwards washed off with 

 sponge and water, never failed to stop its progress and 

 expedite the formation of a scab. 



" I have already subjected two hundred and eleven of 

 my patients to the action of variolous matter, but every one 

 resisted it. 



" The result of my experiments (which were made with 

 every requisite caution) has fully convinced me that the 

 true cow-pox is a safe and infallible preventive from the 

 smallpox; that in no case which has fallen under my ob- 

 servation has it been in any considerable degree trouble- 

 some, much less have I seen any thing like danger ; for in 

 no instance were the patients prevented from following 

 their ordinary employments. 



" In Dr. Woodville's publication on the cow-pox I notice 

 an extraordinary fact. He says that the generality of 

 his patients had pustules. It certainly appears extremely 

 extraordinary that in all my cases there never was but 

 one pustule, which appeared on a patient's elbow on the 

 inoculated arm, and maturated. It appeared exactly like 

 that on the incised part. 



" The whole of my observations, founded as it appears 

 on an extensive experience, leads me to these obvious 

 conclusions; that those cases which have been or may be 

 adduced against the preventive powers of the cow-pox 

 could not have been those of the true kind, since it must 

 appear to be absolutely impossible that I should have suc- 

 ceeded in such a number of cases without a single ex- 

 ception if such a preventive power did not exist. I cannot 

 entertain a doubt that the inoculated cow-pox must quickly 

 supersede that of the smallpox. If the many important 

 advantages which must result from the new practice are 

 duly considered, we may reasonably infer that public bene- 

 fit, the sure test of the real merit of discoveries, will render 

 it generally extensive. 



" To you, Sir, as the discoverer of this highly beneficial 

 practice, mankind are under the highest obligations. As 

 a private individual I participate in the general feeling; 

 more particularly as you have afforded me an opportunity 







