'I have been told that this very method was proposed in the "Gentleman's Magazine" many years ago, but have not the book on board. Frezier, in his voyage to the South Sea, describes a contrivance of the Peruvian Indians upon the same principles, plate 31, p. 273, but his drawing and plan are difficult to understand, if not actually very faulty, and his description is nothing; the drawing may serve, however, to give an idea to a man who has never seen a thing of the kind.'