Joseph is reported to have translated the BOM with a pair of magic spectacles, dictated to Cowdery behind a curtain.
"The Book of Mormon. Story of the Man who First Printed It," Detroit Post and Tribune, December 3, 1877 in The American Bookseller 4 (December 15, 1877): 617-618
Upon the title page appears the name of Joshua Smith as “Author and Proprietor.” In all subsequent editions he appears simply as “Translator.” This change was rendered necessary to carry out the theory afterward adopted that Smith dug up these writings and translated them from “reformed Egyptian” by means of a pair of supernatural spectacles. . . . As he claimed to be the author of the “Book of Mormon” his story was that by the aid of his wonderful stone he found gold plates on which were inscribed the writings in hieroglyphics. He translated them by means of a pair of magic spectacles which the Lord delivered to him at the same time that the golden tablets were turned up. But nobody but Joe himself ever saw the golden tablets or the far-seeing spectacles. He dictated the book, concealed behind a curtain, and it was written down by Cowdery. This course seemed to be rendered necessary by the fact that Joe did not know how to write.