Edward Jenner, art English physician, born at Berkeley, Gloucestershire, May 17, 1749, died there, Jan. 26, 1823. He was the third son of the Rev. Stephen Jenner, vicar of Berkeley, and, having evinced a taste for the study of natural history and medicine, he was apprenticed at the age of 14 to a surgeon in Sudbury, near Bristol, with whom he remained seven years. At the age of 21 he went to London and became a pupil of John Hunter, then rising into eminence as a surgeon and physiologist, with whom he remained two years, and between whom and himself a lasting friendship was established. In the interval he was employed, at the recommendation of Sir Joseph Banks, to arrange the specimens of natural history brought back by Capt. Cook from his first voyage of discovery; and he received the appointment of naturalist to the expedition which sailed in 1772. He declined this offer, and in 1773 returned to Berkeley, where he established himself as a surgeon. In 1792 he procured from the Scottish university of St. Andrews the degree of M. D., and thenceforth devoted himself to the practice of medicine.

As early as during his apprenticeship at Sudbury his attention had been directed to the subject of a preventive of smallpox, by hearing a young countrywoman, who had come to his master's surgery for advice, say that she could not take that disease because she had already had the cowpox. Upon inquiry he ascertained that in Gloucestershire persons engaged in milking cows frequently had the cowpox, a mild disorder of the eruptive kind appearing on the udder of the animal, and communicated in a similar form to their hands; that it had never been known to prove fatal when thus communicated; and that the belief was common among the agricultural classes that whoever had taken the disease was secure against the infection of smallpox. He immediately commenced a serious examination, and was soon led to conjecture that cowpox, as the milder disease, might advantageously supersede the inoculated smallpox, which had been introduced about 50 years before; and that as the latter is rendered less virulent by inoculation, so the former, introduced in the same way, might be milder than the casual complaint, and yet retain its protecting power.

Upon going to London in 1770 he communicated this conjecture to Hunter, who made public mention of it in his lectures, but advised his pupil "not to think, but try." Upon returning to Berkeley he pursued the subject for many years, making a thorough study of varioloid eruptions. It was not until after frequent experiments that he ascertained that only one form of the eruption on the cow's udder had the property of protecting from the smallpox, and such was his faith in his discovery that several of these experiments were made upon his own son, a boy under six years of age. During all this time he met with little encouragement from physicians. Having satisfied himself of the efficacy of inoculation with the virus of the cowpox to prevent the smallpox, he next ascertained with equal certainty that the former disease could be communicated from one human being to another, without having recourse to the original vaccine matter. On May 14, 1796, he vaccinated a boy eight years of age with virus taken from a pustule on the hand of a milkmaid, who had been infected by her master's cow. On July 1 the boy was inoculated for the smallpox, and, as Jenner had predicted, without the slightest effect; and he lived to be inoculated 20 times for the smallpox, with the same result in each case.

For two years afterward he continued his experiments in this direction, and in 1798 went to London. His reception was disheartening in the extreme. Not only did the doctors refuse to make trial of the process, but the discoverer was accused of an attempt to "bestialize" his species by introducing into their system diseased matter from a cow's udder; vaccination was denounced from the pulpit as "diabolical;" and the most monstrous statements respecting its effects were disseminated and believed. At the end of three months he returned to Berkeley, and published his " Inquiry into the .Causes and Effects of the Variolse Vaccinae,"giving details of 16 cases of the casual and 7 of the inoculated disease. The facts described were incontrovertible; but the first impulse toward the adoption of the new practice was given by the successful vaccination of several persons in London by Mr. Cline, a surgeon, with whom Jenner on his return to Berkeley had left some vaccine lymph; and so sudden was the reaction in favor of Jenner, that in less than a year after his departure from London a manifesto expressive of confidence in his discovery was signed by 73 of the most eminent practitioners of the metropolis.

Several of his medical brethren undertook to rob him of the merit of his discovery; and one of these, a Dr. Pearson, in cooperation with Dr. Woodville, physician to the smallpox hospital, brought vaccination into temporary disrepute by using and distributing matter from persons who had been inoculated with smallpox a few days after vaccination, and before the vaccine matter had taken a sufficient hold. Jenner promptly exposed this mistake in his "Continuation of Facts and Observations relating to the Variolse Vaccinae" (1800). In 1800-'l the "Inquiry" was translated into the principal continental languages, and within the next five years flattering testimonials from crowned heads and scientific bodies poured in upon him in abundance, and his discovery was hailed as an incalculable benefit to the human race. In 1802, not without considerable opposition, a parliamentary grant of £10,000 was voted to him; and so encouraging did his prospects appear that in 1803 he took a house in London, with a view of commencing practice there. He was however deceived in his expectations, and returned in the succeeding year to Berkeley, where he continued as before to vaccinate gratuitously all poor persons who applied to him on stated days.

The royal Jennerian society for the encouragement of vaccination was established in 1803, with himself as president, but was subsequently merged in the national vaccine establishment. So inadequate had been the parliamentary grant to compensate him for his outlays and sacrifices in the prosecution of his discovery, that in 1807 a further grant of £20,000 was voted him, and he subsequently received between £7,000 and £8,000 from India. He died suddenly of apoplexy. His statue was placed in Trafalgar square, London, in 1858. His life by Dr. John Baron, with his correspondence, was published in 1827 (2 vols. 8vo; 2d ed., 1838).