The horizon always appears to be on a level with our eye, and seems to rise as we rise, until at length the elevation of the circular boundary line of the sight becomes so marked that the earth assumes the anomalous appearance as we have said of a concave rather than a convex body."- Mayhew's Great World of London. "Another curious effect of the aërial ascent was that the earth, when we were at our greatest altitude, positively appeared concave, looking like a huge dark bowl, rather than the convex sphere such as we naturally expect to see it. At the greatest elevation I attained, which was about a mile-and-a-half, the appearance of the world around me assumed a shape or form like that which is made by placing two watch glasses togetherīy their edges, the balloon apparently in the central cavity all the time of its flight at that elevation."- Wise's Aëronautics. "THE APPARENT CONCAVITY OF THE EARTH AS SEEN FROM A BALLOON.-A perfectly-formed circle encompassed the visibly planisphere beneath, or rather the concavo-sphere it might now be called, for I had attained a height from which the earth assumed a regularly hollowed or concave appearance-an optical illusion which increases as you recede from it. well known to sea-going travellers that nothing more need be said in its support but the appearance from a balloon is only familiar to a very few observers, and therefore it will be useful to quote the words of some of those who have written upon the subject.
He seems to be in the centre of a large concavity-a vast watery basin-the circular edge of which expands or contracts as he takes a higher or lower position. If he takes a position where the water surrounds him-as, on the deck or the mast-head of a ship out of sight of land, or on the summit of an island far from the mainland-the surface of the sea appears to rise up on all sides equally, and to surround him like the walls of an immense amphitheatre. 25, H, H, the sea horizon, which rises and falls with the observer, and is always on a level with his eye. If a good plane mirror be held vertically in the opposite direction, the horizon will be reflected as a well defined mark or line across the centre, as represented in fig. Sea, the surface appears as a vast inclined plane rising up from beneath us, until in the distance it reaches the level of the eye, and intercepts the line-of-sight. If we stand upon the deck of a ship, or mount to the mast-lead, or ascend above the earth in a balloon and look over the Sacred Texts Earth Mysteries Index Previous Next Experiments Demonstrating the True Form of Standing Water, and Proving the Earth to be a Plane: Experiment 10 Zetetic Astronomy, Earth Not A Globe: Chapter II.