From Benjamin Waterhouse
Cambridge July 24th. 1801
The thread enclosed in this Quill was imbued in the vaccine virus on Thursday Evening the 23d of July. At the same time the needle was infected in the same fluid and it is highly probable will communicate the disease if it be thrust under the scarf skin, and drawn slowly & gradually through it.
RC (DLC); addressed: “The President of the United States Washington”; franked; postmarked Boston; endorsed by TJ as received 6 Aug. and so recorded in SJL.
On 26 July, Waterhouse sent another supply of cowpox with the following note: “Vaccine virus on a needle, and on the thread, taken Sunday morning 26th. of July, from a young and healthy subject; on the 8th. day of the disease, another inoculation,” with weather “moderate, and rainy for several days in succession” (RC in DLC; addressed: “The President of the United: States Washington”; franked; postmarked Boston, 27 July; endorsed by TJ as received 6 Aug. and so recorded in SJL).