Mulholland records the account of the BOM translation; Joseph used instruments he called U&T.
“History, circa June 1839–circa 1841 [Draft 2],” 5, 9, 11, The Joseph Smith Papers website, accessed July 28, 2021
He said there was a book deposited written upon gold plates, giving an account of the former inhabitants of this continent and the source from whence they sprang. He also said that the fullness of the everlasting Gospel was contained in it as delivered by the Saviour to the ancient inhabitants. Also that there were two stones in silver bows and these put into a breast plate which constituted what is called the Urim & Thummin deposited with the plates, and that was what constituted seers in ancient or former times and that God <had> prepared them for the purpose of translating the book. . . . immediately after my arrival there I commenced copying the characters of all the plates. I copyed a considerable number of them and by means of the Urim and Thummin I translated some of them which I did between the time I arrived at the house of my wife’s father in the month of December [1827], and the February following. . . . Mr [Martin] Harris . . . returned again to my house about the twelfth of April, Eighteen hundred and twenty eight, and commenced writing for me while I translated from the plates, which we continued untill the fourteenth of June following, by which time he had written one hundred and sixteen <pages> of manuscript on foolscap paper. . . . I did not however go immediately to translating [in the winter of 1828], but went to laboring with my hands upon a small farm which I had purchased of my wife’s father, in order to provide for my family. . . .