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. XVIII.--JOHN BAKER, five years old. 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. Mark the assumption, “_The virus from the Horse is not to be relied upon as rendering the system secure from variolous infection, but the matter produced by it on the nipples of the Cow is perfectly so!_” Such was Jenner’s method of induction! How could he leave the question undecided? Why not have waited until little Baker recovered from his fever? or why not have inoculated another work-house child with Horsegrease? The true sons of science do not rush into print in such shameless deshabille. XIX.--WILLIAM SUMMERS, aged five and a half. Inoculated 16th March, 1798, from the nipple of one of the Cows infected with Horsegrease by Haynes. Subsequently inoculated with Smallpox without effect. XX.--WILLIAM PEAD, aged eight. Inoculated, 28th March, from Summers. Subsequently inoculated with Smallpox without effect. XXI.--HANNAH EXCELL, aged seven.