onging to the farm began to have sore heels, which Merret
frequently attended. The cows soon became affected with the Cow Pox,
and soon after several sores appeared on his hands. Swellings and
stiffness in each axilla followed, and he was so much indisposed for
several days as to be incapable of pursuing his ordinary employment.
Previously to the appearance of the distemper among the cows there
was no fresh cow brought into the farm, nor any servant employed who
was affected with the Cow Pox.

In April, 1795, a general inoculation taking place here, Merret was
inoculated with his family; so that a period of twenty-five years had
elapsed from his having the Cow Pox to this time. However, though the
variolous matter was repeatedly inserted into his arm, I found it
impracticable to infect him with it; an efflorescence only, taking on
an erysipelatous look about the centre, appearing on the skin near
the punctured parts. During the whole time that his family had the
Small Pox, one of whom had it very full, he remained in the house
with them, but received no injury from exposure to the contagion.

It is necessary to observe, that the utmost care was taken to
ascertain, with the most scrupulous precision, that no one whose case
is here adduced had gone through the Small Pox previous to these
attempts to produce that disease.

Had these experiments been conducted in a large city, or in a
populous neighbourhood, some doubts might have been entertained; but
here, where population is thin, and where such an event as a person's
having had the Small Pox is always faithfully recorded, no risk of
inaccuracy in this particular can arise.

_CASE II._

SARAH PORTLOCK, of this place, was infected with the Cow Pox, when a
Servant at a Farmer's in the neighbourhood, twenty-seven years
ago[1].

In the year 1792, conceiving herself, from this circumstance, secure
from the infection of the Small Pox, she nursed one of her own
children who had accidentally caught the disease, but no
indisposition ensued.--During the time she remained in the infected
room, variolous matter was inserted into both her arms, but without
any further effect than in the preceding case.

[Footnote 1: I have purposely selected several cases in which the
disease had appeared at a very distant period previous to the
experiments made with variolous matter, to shew that the change
produced in the constitution is not affected by time.]

_CASE III._