Martin Harris told Anthony Metcalf that Joseph used a stone in a hat and would spell out the English words.
Anthony Metcalf, Ten Years before the Mast. Shipwrecks and Adventures at Sea. Religious Customs of the People of India and Burmah’s Empire. How I Became a Mormon and Why I Became an Infidel (Malad City, Idaho: n.p., 1888), 70–71
He told me all about the translating of the Book of Mormon, and said he had given $5,000 towards its publication. He said: “I never saw the golden plates, only in a visionary or entranced state. I wrote a great deal of the Book of Mormon myself, as Joseph Smith translated or spelled the words out in English. Sometimes the plates would be on a table in the room in which Smith did the translating, covered over with a cloth. I was told by Joseph Smith that God would strike him dead if he attempted to look at them, and I believed it.”