The vaccine matter, which you were so good as to transmit to me 4 or 5 weeks ago, on quills & on thread, has been tried. I communicated the genuine disease with some from one of the tooth-picks, but am not absolutely certain that it ever took from the thread. This induces me to make an observation that may be useful to your inoculators.

I was, at first sight, suspicious of the goodness of the thread you sent me merely from its quantity; for if I understood you right, it was all taken from one patient. I think myself pretty fortunate if I obtain 2, or 3 inches of perfectly infected thread from one patient. Frequently I can procure not more than two inches, whereas the phial you sent me contained, perhaps, as many feet, and that two of very fine thread. I set more value on two inches of coarser thread repeatedly soaked in the fluid, so as to have acquired the stiffness of a wire; in which case, the contortions of the thread are nearly obliterated by the coat of matter, whereas that which I received scarcely agglutinated the fibrillæ of the cotton. My requesting a sample of the virus from your own cases, was with a view of demonstrating that your cases were genuine; and of judging if your physicians conducted the process of taking the virus (for transportation especially) in the manner, which we find by experience to be best. They will, therefore, I hope, excuse my observing that it is better to imbue repeatedly an inch or two very well, than merely to moisten ten times that quantity. By the first procedure they will very seldom, if ever be disappointed, by the latter frequently.

I have gone on inoculating with an almost undeviating success throughout the spring, summer, & this autumn. When I used the fresh virus, warm from the pustule, I never failed; but with the thread, I, in the very hot weather, was sometimes foiled.

The enemies of this new inoculation (for in this inferior walk, prejudice, envy, & other unworthy passions, will for a while hang heavily on the wheel destined to bring forth anything new in science) have lately rallied round one of our principal small:pox-inoculators, and gave a momentary check to the progress of truth & humanity, by publishing five cases (clearly spurious, except to the eye of ignorance) to whom he gave the small-pox. By placing a fact with it’s wrong end foremost, some uneasiness was created in the public mind. Rumour generated from a simple fact, so placed, an apparently formidable structure, which on close examination was, however, discovered to have neither foundation, nor sides to it,—a mere illusion, calculated to deceive, & to retain a little while longer their old friend, the smallpox. Not but what there are still many unbelievers among that class of people, where we may not dispair of making them believe any thing but truth.

I have enclosed part of a News-paper containing some observations on this professional opposition. In the course of a few weeks, I propose to publish a Report of the progress of the vaccine-inoculation during the year 1801, a copy of which I will transmit to you: after which, as I have attained the ultimate object of my views, the planting the true Kine-pox in the most populous of the Southern-States, under the most favourable auspices, I shall have no further occasion to encroach on your valuable time, but conclude with wishing you long to possess the highest honor our country can bestow, with health to enjoy it.