Show Problem for Inventors How Bow can the captain of a dirigible balloon know his altitude Is a problem problem lem hem that Cave Cave Brown-Cave put to the British association for solution recently recent recent- ly The barometer ter Is generally used but as ns' ns It registers the sea-level sea air pressure only of the point of departure departure departure depar depar- ture and as the balloon Is moving at nt GO 60 or 70 miles an hour it may be quite wrong after being up for a short time A captain recently thought he be was fully tully feet up when actually he was almost touching the water |