Thomas Wood Smith heard that David Whitmer frequently saw that Joseph translated the characters on the plates with the Urim and Thummim.

I personally heard him state, in Jan. 1876 in his own house in Richmond, Ray Co. Mo. . . . that he saw Joseph translate, by the aid of the Urim and Thummim, time and again, and he [David] then produced a large pile of foolscap paper closely written in a very fair hand, which he declared was the manuscript written mainly by Oliver Cowdery and Martin Harris, as the translation was being read by the aid of the Urim and Thummim of the characters on the plates by Joseph Smith, which work of translation and transcription he frequently saw.