John Corrill describes how Martin Harris took characters to NY to be translated, but that Joseph translated the BOM using two stones set in a box.

John Corrill

John Corrill, A Brief History of the Church of Christ of Latter Day Saints (Commonly Called Mormons;) Including an Account of Their Doctrine and Discipline; with the Reasons of the Author for Leaving the Church (St. Louis: By the author, 1839), 7, 12, The Joseph Smith Papers website, accessed August 11, 2021

John Corrill
Joseph Smith, Jr., Oliver Cowdery, John Corrill, Peter Whitmer, Jr., Ziba Peterson, Parley P. Pratt
General Public

Sometime in the fall of 1830, Oliver Cowdery, Parley P. Pratt, Peter Whitmer and Tiba [Ziba] Peterson, came through the county of Ashtabula, Ohio, where I then resided, on their way westward. They professed to be special messengers of the Living God, sent to preach the Gospel in its purity, as it was anciently preached by the Apostles. They had with them a new revelation, which they said had been translated from certain golden plates that had been deposited in a hill, (anciently called Camorah,) in the township of Manchester, Ontario county, New York. . . . . . . through much difficulty, on account of persecution and poverty, he [Joseph Smith] translated it by degrees, with the assistance of Oliver Cowdery and others, who wrote as he dictated. If I remember right, the language in which it was written on the plates, was the reformed Egyptian. And Martin Harris, who contributed much towards the publication of the Book, drew off several of the characters on paper, took them to the learned in New York, to see if they could be translated, but was requested to bring them the plates, which Smith was forbidden to do of the Lord, but was commanded to translate them himself, which he did, by the help of what he calls the Urim and Thummim, two stones set in a bow, and furnished by an Angel for that purpose. After finishing the translation, the plates and stones of Urim and Thummim were again taken and concealed by the Angel for a wise purpose, and the translation published to the world in the winter of A. D. 1829 and ’30.

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