Said Jenner, “The more accurately to observe the progress of the infection, I selected a healthy boy, about eight years old, for the purpose of INOCULATION FOR THE COWPOX.” The matter was inserted into his arm by two incisions, barely penetrating the cutis, each about half an inch long. The inoculation “took,” and was followed by a chill, loss of appetite, headache, and restless sleep. On the 1st of July, the poor lad was inoculated with Smallpox, and again several months afterwards, it is said, without effect.
Here [wrote Jenner] my researches were interrupted till the spring of the year 1798, when, from the wetness of the early part of the season, many of the farmers’ Horses were affected with sore heels, in consequence of which Cowpox broke out among several of our dairies, which afforded me an opportunity of making further observations upon the curious disease.
About the latter end of February, 1798, William Haynes and Thomas Virgoe, having to wash a Mare with sore heels, were infected with Grease, and described their sensations as much the same as when they were inoculated with Smallpox. Their infection proved that if Grease was good against Smallpox, Smallpox was not good against Grease. Haynes was employed as a milker, and Pox broke out among his master’s Cows about ten days after he had first assisted in washing the Mare’s heels.
Inoculated, 16th March, 1798, with matter taken from a pustule on the hand of the aforesaid Thomas Virgoe poisoned with Grease from the Mare’s heels. “He became ill on the sixth day with symptoms similar to those excited by Cowpox, and on the eighth was free from indisposition.”
On this case of Horsegrease inoculation, Jenner observed--
We have seen that the virus from the Horse is not to be relied upon as rendering the system secure from variolous infection, but that the matter produced by it on the nipple of the Cow is perfectly so. Whether the virus passing from the Horse through the human constitution, as in the present instance, will produce a similar effect remains to be decided. This would have been effected, but the boy was rendered unfit for Smallpox Inoculation from having felt the effects of a contagious fever in a work-house soon after this experiment was made.