In answer to your letter of the 30th ult. [ultimate], William Swainson was an "F.R.S" [Fellow of the Royal Society]. He was elected a Fellow of the Society on December 14, 1820, and admitted on February 1, 1821. We have no means of ascertaining his address at that date.
Asst. Sec. R.S. [Assistant Secretary, Royal Society]'.