I know not if I acknowledged the receipt of your letter of the 8th. ulto. in the hasty scrawl I lately wrote from Boston. That of the 14th. gave me pleasure inexpressible, as it informed me that you had succeeded in planting the benign remedy against the small pox in the vast region of Virginia. I have written to Dr. Wardlaw on the important subject of preserving the active fluid-virus for inoculation, in constant succession from patient to patient. I wish he had inoculated as many as he possibly could, from the pustule, and not trusted to the thread, as the fresh fluid never, or very rarely fails communicating the infection, even when no other instrument is used than a cambric:needle.

I have referred Dr. Wardlaw to the letter I wrote to you at Washington for more minute directions. I have repeated to him, and hope to be excused for re-iterating it here, to take the matter on the 8th. day, nay the 7th. if possible, and never later than the 9th. The efflorescence is a sign that the absorption has commenced, and the nicety of the business is to take the virus just before that period. I have watched this process with a microscope in a number of persons whom I had taken into my house for this express purpose, and experience has now taught me a sure procedure, somewhat different from my early theory, which was to take the matter at the very acme of the inflammation. I now take it before the virus is so far absorbed as to affect the lymphatics in the arm-pit with pain; and by so doing I always succeed. In consequence of the hint in your letter just on your departure from Washington, I sent Dr Gantt the virus in a phial of water, but have not heard of its reception. This matter I took on a cool & rainy day and put it up with great care, and can hardly conceive that it should fail. The weather has been oppressively hot,—98 in the shade! an occurrence not easily accounted for in this northern latitude, and in our situation. On a journey this time 12 months, I found it as hot an hundred miles east of us, and more like a sirocco than any thing I ever felt. “There is something in this which our philosophy has never dreamt of.”—I carefully avoided taking matter for transportation during such hot days, for I presume the mercury must have risen to 106, in the open fields

I may be mistaken, but I at present believe that my thus sending the vaccine matter to President Jefferson has forwarded the practice in Virginia at least a year, if not two. The rivalship of physicians, the desire of taking, and keeping the lead in this new inoculation have retarded the advancement of the true inoculation, while it has diffused the spurious far & wide. I therefore presume that a number of decidedly perfect cases in the neighborhood of Monticello will give the genuine disease a currency through Virginia. The vaccine inoculation is progressing at Newfoundland. The physician general at Halifax has just written to me on the subject of introducing it there. At Geneva it is now the custom with the ministers of religion to impress on the minds of every parent, who presents a child for baptism the duty of giving it this newly discovered disease. The minister of the interior, directed Professor Odier to make him a report of the state of vaccinism in France. But the most eloquent production I have yet seen on the subject, is by a physician at Hamburgh, so that the practice is becoming universal in Europe. What a blessing will this discovery be to the inhabitants of the African side of the mediterranean where the small-pox has always raged with a peculiar malignity! We already know that the kine-pox has preserved its characteristic mildness at Minorca.

I have had a number of communications from different parts of New England, tending to induce a belief, that this disease has been found among the kine of our own country. I am not, however, entirely convinced of it. I gave full credence to one account transmitted to me by our Attorney General. I even sent the history to London, which may possibly be already published. I communicated it also to the Massachusetts Medical society as a proff of the domestic origin of the kine pox. And it is not many days since I discovered that the cow was inoculated by a mischevous medical-pupil, who took this method to convince an old, unbelieving country practitioner that there really did exist such a disease. This rustic physician’s daughters were his milk maids. They being soon disabled from milking the diseased cow, their mother performed that office and took the disorder also In the height of the disorder they were seen by Chief Justice Dana, Judge Sulivan, and some other gentlemen who had seen the disease in their own families. I gave more credit to this account coming from gentlemen belonging to that order whose very essence is evidence, than if it were related by physicians, yet my account sent to England must be followed by this explanation.

There appeared in almost all the news-papers in the Union a paragraph saying that a Dr. Lacci had discovered the vaccine virus among the Leaves in Switzerland, to which the printers added three notes of admiration!!!—I wrote to one of the Boston printers that he might change the L. into a B. and then erase the three notes of admiration.

This epizootic distemper has existed so long in Ireland as to be known there by a Celtic name, viz. “Shinnaugh”; which word is found on dissection to mean “a Cow’s. teat.” To a knowledge of this disease has been connected an opinion that persons once affected with the Shinnaugh could never take the small pox. But Dr. Jenner a learned, skillful, and philanthropic physician was the first who took this knowledge so long vaguely floating on the breath of the vulgar and impressed upon it the stable form of science. He, with a Franklian sagacity first transferred it from the brute to the human kind, and demonstrated it to be a perfect security against the small pox. This extraordinary fact came forth from his masterly hands in so perfect a form, that were all other writings on the Cow-pox but his, destroyed, posterity would have a clear & unconfused idea of this singular disease & its saluteferous consequences.

I am preparing a second pamphlet, being “Observations on the local appearance, symptoms, & mode of treating the Variola Vaccinæ, with some rules for determining the true pustule from the spurious,” but my collegiate duties will scarcely allow me to publish it very soon, my course on Natural History having just commenced, and when that terminates my medical Lectures begin

In the course of my researches, I have learnt that the pustular disease denominated Chicken pox originated in those domestic birds, which having no specific name in the english language are called by the general one of fowls, or by the still more vague one of Cocks & Hens. It originated in Hyndostan. The small pox and that disease in the poultry having, with the natives, the same denomination viz. “gooty.”

With the highest respect for your station and character I remain your very humble servt.