I've been reading "A catalogue of the Washington collection in the Boston Athenæum," which describes what books President Washington read, and if he made any comments or wrote any letters about them.
[AMORY, Thomas. Eccentric English writer, 1691 (?)-1788.]
The Life of John Buncle, Esq; containing Various Observations and Reflections, made in several Parts of the World, and many extraordinary Relations. London: printed for J. Johnson and B. Davenport. M.dcc.lxvi. Vol. I. iv, (iii)-ix, (7), 511 pp. Vol. II. (16), 532 pp. 8°.
"The book is a literary curiosity, containing an extraordinary medley of religious and sentimental rhapsodies, descriptions of scenery, and occasional fragments of apparently genuine autobiography. 'The soul of Rabelais,' says Hazlitt, ' passed into John (Thomas) Amory.' The phrase is suggested by Amory's rollicking love adventures. He marries seven wives in the two volumes of Buncle, generally after a day's acquaintance, and buries them as rapidly. They are all of superlative beauty, virtue, and genius, and, in particular, sound Unitarians. A great part of the work is devoted to theological disquisition, showing considerable reading in defence of 'Christian deism.' Much of his love-making and religious discussion takes place in the north of England, and there is some interest in his references to the beauty of the lake scenery. His impassable crags, fathomless lakes, and secluded valleys, containing imaginary convents of Unitarian monks and nuns, suggest the light-headed ramblings of delirium." — Leslie Stephen.
Washington undoubtedly read this book, as he takes care to note the interruption of the continuity of the narrative caused by the transposition of the parts in binding. The volumes bear no marks of frequent reading or use; on the contrary, they have a very fresh and clean appearance.
Update: Before someone beats me to it in the comments, the book, apparently, can be read here.