John Murdock reports on Sidney Rigdon saying how Joseph was illiterate, but when he puts the spectacles on, he can produce "a literal translation of the writing upon the gold plates."
[John Murdock], “Sidney Rigdon. A Report of a Lecture He Delivered Forty Years Ago in Meadville [Pennsylvania]—Rigdon’s Account of Joe Smith’s Revelation,” Pittsburgh Telegraph, August 24, 1876 in John W. Welch, "Documents of the Translation of the Book of Mormon" in John W. Welch, ed., Opening the Heavens: Accounts of Divine Manifestations, 1820-1844, 2nd ed. (Provo, UT: BYU Studies, 2011), 218
Joe, he said, was a very illiterate man, was unable either to read or write; but when he put on his nose the prophet’s spectacles, and took the gold plates one by one, letter by letter and word by word presented themselves, and with the aid of an amanuensis the Bible that he held in his hand was a literal translation of the writing upon the gold plates.