William Charles Wells (1757-1817) was one of the foremost, and forgotten, American scientists of the eighteenth century. He should be acknowledged as laying the foundations for modern studies of vestibular function as well as eye movements. This book reprints his Essay on single vision with two eyes (1792) and his own Memoir of his life (1818). Wells' essay on natural selection is reprinted as an Appendix. Wells' experiments and observations on natural phenomena will surprise students of science because of their modernity.