l-pox
being casually mentioned, she remarked she could not take the
small-pox because she had had cow-pox; and he then learnt that it
was a popular notion in that district, that milkers who had been
infected with a peculiar eruption which sometimes occurred on the
udder of the cow, were completely secure against the small-pox. The
medical gentlemen of the district told Jenner that the security
which it gave was not perfect; and Sir George Baker, the physician,
treated it as a popular error. But Jenner thought otherwise; and
although John Hunter and other eminent surgeons disregarded the
subject, Jenner pursued it. He found at Berkeley that some persons,
to whom it was impossible to give small-pox by inoculation, had had
cow-pox; but that others who had had cow-pox yet received small-pox.
This led to the doctor's discovery that the cow was subject to a
certain eruption, which had the power of guarding from small-pox;
and next, that it might be possible to propagate the cow-pox, and
with it security from the small-pox, first from the cow to the human
body, and thence from one person to another. Here, then, was an
important discovery, that matter from the cow, intentionally
inserted into the body, gave a slighter ailment than when received
otherwise, and yet had the same effect of completely preventing
small-pox. But of what advantage was it for mankind that the cows of
Gloucestershire possessed a matter thus singularly powerful? How
were persons living at a distance to derive benefit from this great
discovery? Dr. Jenner, having inoculated several persons from a cow,
took the matter from the human vesicles thus produced, and
inoculated others, and others from them again; thus making it pass
in succession through many individuals, and all with the same good
effect in preventing small-pox.

An opportunity occurred of making a trial of the latter on May 14,
1796 (a day still commemorated by the annual festival at Berlin),
when a boy, aged eight years, was vaccinated with matter from the
hands of a milkmaid; the experiment succeeded, and he was inoculated
for small-pox on July 1st following without the least effect. Dr.
Jenner then extended his experiments, and in 1798 published his
first memoir on the subject. He had originally intended to
communicate his results to the Royal Society, but was admonished not
to do so, lest it should injure the character which he had
previously acquired among scientific persons by his paper