At the meetings of these societies Jenner would often bring forward the reported prophylactic virtues of cowpox, and earnestly recommend his medical friends to inquire into the matter. All his efforts, however, failed to induce them to take it up; and the subject became so distasteful to them that they at one time threatened to expel him if he continued to harass them with so unprofitable a subject.
Dr. Jenner did not marry till March 6, 1788, when Miss Catherine Kingscote, a lady belonging to a well-known Gloucestershire family frequently furnishing representatives to Parliament, became his wife. The union was very happy, but Mrs. Jenner’s delicate health for many years caused great anxiety and needed constant attention.
In 1792 Jenner became M.D. of St. Andrews, with the view of giving up much of his fatiguing general practice. In 1794, at the age of forty-five, he suffered from a severe attack of typhus fever, which threatened to prove fatal. At this time the experiments in proof of vaccination had not been made, and if he had died, the world in all probability might have waited long for the introduction of this great novelty.
Many who learn that vaccination was made known to the world in 1798, when Jenner was forty-nine years old, do not know that the subject attracted his attention in his youthful days as a country surgeon’s apprentice, and that his faculties were ever after engaged upon the matter at every convenient opportunity. He repeatedly mentioned the subject of cowpox to his great teacher, John Hunter, when studying with him in London. Hunter never damped the ardour of a pupil by suggesting doubts or difficulties; but it does not appear that he was specially impressed by what he heard. Yet he made known Jenner’s information and opinions both in his lectures and to his friends. But for many years Jenner’s ideas were poohpoohed by medical and other authorities whom he met in his country practice. They believed many had had smallpox after cowpox, and that the supposed protective influence of the latter was due to something in the constitution of the individual.
Not till 1780 did Jenner fully disclose to his devoted friend Edward Gardner his hopes and fears about what he felt to be his great life-work. He then described to him the various diseases which attacked milkers when they handled diseased cows, and especially that form which afforded protection against smallpox; and with deep and anxious emotion expressed his hopes of being able to propagate this latter form from one human being to another, so as to bring about the total extinction of smallpox.
The exceeding simplicity of the ultimate discovery makes it difficult for us nowadays to imagine the circumstances under which Jenner had to grope his way in the imperfect twilight, and the perplexities by which he was beset in arriving at true conclusions. Both his own observation and that of other medical men of his acquaintance proved to him that what was commonly called cowpox was not a certain preventive of smallpox. But he ascertained by assiduous inquiry and personal investigation that cows were liable to various kinds of eruptions on their teats, all capable of being communicated to the hands of the milkers; and that such sores when so communicated were all called cowpox. But when he had traced out the nature of these various diseases, and ascertained which of them possessed the protective virtue against smallpox, he was again foiled by learning that in some cases when what he now called the true cowpox broke out among the cattle on a dairy farm, and had been communicated to the milkers, they subsequently had smallpox.
It was this repeated failure to arrive at a perfect result which perhaps gave the stimulus that led Jenner to ultimate triumph. The fact that he was on the scent of a discovery which in some form had a promise of indefinite blessing, made him redouble his efforts when most perplexed. He conceived the idea that the virus of the cowpox itself might undergo changes sufficient to deprive it of its protective power, and yet enable it to communicate a disease to the milker. Thus he at last came on the track of the discovery that it was only in a certain condition of the pustule that the virus was capable of imparting its protective power to the human constitution.
Having thus steered his way safely through all the pitfalls which might have destroyed the accuracy of his results, Jenner was able to go on to the next stage, that of putting his theory to the test. It is singular how long he was before he had an opportunity of further experiment. In 1788 he showed a drawing of the cowpox as it occurred in milkers to Sir Everard Home and others in London. Various eminent medical men, Cline, Adams, Haygarth, heard of and discussed the matter, and encouraged Jenner’s inquiries. But it was not till May 14, 1796, that he had an opportunity of transferring cowpox from one human being to another. Sarah Nelmes, a dairymaid who had been infected from her master’s cows, afforded the matter, and it was inserted by two surperficial incisions into the arms of James Phipps, a healthy boy about eight years old. The cowpox ran an ordinary course with no ill effect, and in July Jenner writes to Gardner: “The boy has since been inoculated for the smallpox, which, as I ventured to predict, produced no effect. I shall now pursue my experiments with redoubled ardour.”
Jenner did not, even now that he had attained to certainty in his own mind, rush precipitately into publicity, although his benevolent desires to avert the scourge of smallpox from humanity strongly urged him to do so. Still less did he yield to the temptation to establish himself as a practitioner with a specialty for warding off smallpox, which might have led him speedily to fortune. He was as if forearmed against the stringent requirements which would be made as to the proofs of such a discovery if made gratuitously public. At this time he says: “While the vaccine discovery was progressive, the joy I felt at the prospect before me of being the instrument destined to take away from the world one of its greatest calamities, blended with the fond hope of enjoying independence and domestic peace and happiness, was often so excessive that, in pursuing my favourite subject among the meadows, I have sometimes found myself in a kind of reverie. It is pleasant to me to recollect that these reflections always ended in devout acknowledgments to that Being from whom this and all other mercies flow.”
Until the spring of 1798 Jenner had no further opportunity of pursuing his inquiries, for the cowpox disappeared from the neighbouring dairies. At last he had matured his research, and it was ready for publication. Before sending it to the printers it was most carefully scrutinised by a number of friends at Rudhall, near Ross, in Herefordshire, the seat of Mr. Thomas Westfaling. Their sympathy encouraged him and their judgment approved of his work, which none who read Jenner’s modest and now classic recital, “An Inquiry into the Causes and Effects of the Variolæ Vaccinæ,” bearing date June 21, 1798, can wonder at. Previous to this date, however, Dr. and Mrs. Jenner had been two months in London, experiencing much mortification from the fact that no one in London could be obtained as a patient to be inoculated with cowpox. Dr. Jenner often stated that his patience had been exhausted on that occasion: and it remained for Henry Cline to perform the first successful vaccination in London. Finding that subsequent inoculation with smallpox failed to give his patient any disease, Cline expressed his opinion that this promised to be one of the greatest improvements ever made in medicine; and he begged Jenner to remove to London, promising him a practice of ten thousand a year. Jenner’s sentiments on this matter are characteristically expressed in the following extract: “Shall I, who even in the morning of my days sought the lowly and sequestered paths of life—the valley, and not the mountain; shall I, now my evening is fast approaching, hold myself up as an object for fortune and for fame? Admitting it as a certainty that I obtain both, what stock should I add to my little fund of happiness? My fortune, with what flows in from my profession, is sufficient to gratify my wishes; indeed, so limited is my ambition and that of my nearest connexions, that were I precluded from future practice I should be enabled to obtain all I want. And as for fame, what is it? a gilded butt, for ever pierced with the arrows of malignancy.”