***Completely revised version of the original 1885 edition*** "If we take a journey down the Chesapeake Bay, by night, we shall see the 'light' exhibited at Sharpe's Island for an hour before the steamer gets to it. We may take up a position on the deck so that the rail of the vessel's side will be in a line with the 'light' and in the line of sight; and we shall find that in the whole journey the light won't vary in the slightest degree in its apparent elevation. But, say that a distance of thirteen miles has been traversed, the astronomers' theory of 'curvature' demands a difference (one way or the other ) in the apparent elevation of the light, of 112 feet 8 inches Since, however, there is not a difference of 100 hair's breadths, we have a plain proof that the water of the Chesapeake Bay is not curved, which is a proof that the Earth is not a globe."