Cowpox was very frequently epizootic in the dairy-farms in the spring.... A great number of instances of the Cowpox in milkers had fallen under his observation, but not a single mortal, or even dangerous, case occurred. There was not a medical man in Gloucestershire, or scarce a dairy-farmer, who did not know from his own experience, or that of others, that those who have suffered the Cowpox are exempt from the agency of the variolous poison. (P. 95.) Dr. Croft likewise told Pearson-- That in Staffordshire to his knowledge, the fact had been long known of the Cowpox, which prevails in that county, affording an exemption of the human subjects from the Smallpox. (P. 35.) Nor did what was so widely believed escape mention in medical literature. Thus Dr. Beddoes, in _Queries concerning Inoculation_, had written in 1795-- I have learnt from my own observation, and the testimony of some old practitioners, that susceptibility to the Smallpox is destroyed by the Cowpox, which is a malady more unpleasant than dangerous. And Dr. Adams, in his treatise on _Morbid Poisons_, 1795, observed-- Cowpox is a disease well known to the dairy-farmers in Gloucestershire. What is extraordinary, as far as facts have hitherto been ascertained, a person infected with Cowpox is rendered insensible to the variolous poison. And Dr. Woodville in his _History of Inoculation_, 1796, argued-- It has been conjectured that the Smallpox might have been derived from some disease of brute animals; and, if it be true that the mange affecting dogs, can communicate a species of itch to man; or that a person, having received a certain disorder from handling the teats of cows, is thereby rendered insensible to variolous infection ever afterwards--then, indeed, the conjecture is not improbable. The belief, moreover, that Cowpox was good against Smallpox, had tempted several to court the disease. The Rev. Herman Drewe wrote to Pearson of himself and Mr. Bragge, surgeon, Axminster, 5th July, 1798-- Mr. Bragge and I endeavoured to try the experiment of inoculating with the matter of the Cowpox, but from the scarceness of the disease, and unwillingness of patients, we were disappointed. (P. 39.) Mr. Dolling of Blandford related that-- Mr. Justings, of Axminster, inoculated his wife and children with matter taken from the teats of a cow that had the Cowpox. In about a week afterwards their arms were very much inflamed, and the patients were so ill that the medical assistance of Mr. Meach, of Cerne, was called for. The patients did well. They were afterwards inoculated for the Smallpox by Mr. Trobridge without effect. (P. 42.) Dr. Pulteney of Blandford informed Pearson that--