Elected a member of the Academy in 1857, Williamson made two donations to the Academy which were set up as special funds. The first was unrestricted, but the second was intended to benefit the library. The “I. V. Williamson Library Fund,” was established in 1875 and gave the interest on $25,000 to be expended for the purchase of books and to help pay the librarian's salary. It is still active and supplies a partial income for library accessions. The contents of this collection are a letter signed E. J. Nolan, 1877 accompanying a book of permanent records of the acquisitions made on the I. V. Williamson Fund from December, 1875 to December, 1878 and accounts and receipts of charges against the Williamson Library Fund, 1888-92.