I recieved on the 24th. Ult. your favor of the 22d. but it is not till this day that I am enabled to comply with your request of forwarding some of the vaccine matter for Doctr. Coxe. on my arrival at Monticello in July I recieved from Dr. Waterhouse of Cambridge some vaccine matter taken by himself, and some which he at the same time recieved from Dr. Jenner of London. both of them succeeded, and exhibited precisely the same aspect and affections. in the course of July and August I inoculated about 70. or 80. of my own family, my sons in law about as many of theirs, and including our neighbors who wished to avail themselves of the opportunity our whole experiment extended to about 200. persons. one only case was attended with much fever, & some delirium, & two or three with sore arms which required common dressings. all these were from accidents too palpable to be ascribed to the simple disease. about one in 5. or 6. had slight feverish dispositions, more perhaps had a little headach, and all of them had swellings of the axillary glands, which in the case of adults disabled them from labour 1. 2. or 3. days. two or three only had from 2. to half a dozen pustules on the inoculated arm & no where else, and all the rest only the single pustule where the matter was inserted, something less than a coffee bean, depressed in the middle, fuller at the edges & well defined. as far as my observation went the most premature cases presented a pellucid liquor the 6th. day, which continued in that form the 6th. 7th. & 8th. days, when it began to thicken, appear yellowish, & to be environed with inflammation. the most tardy cases offered matter on the 8th. day which continued thin & limpid the 8th. 9th. & 10th. days. percieving therefore that the most premature as well as the tardiest cases embraced the 8th. day, I made that the constant day for taking matter for inoculation: say 8. times 24. hours from the hour of it’s previous insertion. in this way it failed to infect in not more I think than 3. or 4. out of the 200. cases. I have great confidence therefore that I preserved the matter genuine, & in that state brought it to Doctr. Gantt of this place on my return, from whom I obtain the matter I now send you, taken yesterday from a patient of the 8th. day. he has observed this rule as well as myself. in my neighborhood we had no opportunity of obtaining variolous matter to try by that test the genuineness of our vaccine matter; nor can any be had here, or Dr. Gantt would have tried it on some of those on whom the vaccination has been performed. we are very anxious to try this experiment for the satisfaction of those here, and also those in the neighborhood of Monticello, from whom the matter here having been transferred, the establishment of it’s genuineness here will satisfy them. I am therefore induced to ask the favor of you to send me in exchange some fresh variolous matter, so carefully taken and done up as that we may rely on it. you are sensible of the dangerous security which a trial with effete matter might induce. I should add that we never changed the regimen nor occupations of those we inoculated. a smiter at the anvil continued in his place without a moment’s intermission, or indisposition. generally it gives no more of disease than a blister as large as a coffee bean, produced by burning, would occasion. sucking children did not take the disease from the inoculated mother. these I think are the most material of the observations I made in the limited experiment of my own family. in Aikin’s book, which I have, you will find a great deal more. I pray you to accept assurances of my esteem & respect.