Airships past and present, together with chapters on the use of balloons in connection with meteorology, photography and the carrier pigeon . Fig. 17.—The statoscope, byGradenwitz. 36 A1KSHIPS PAST AND THE THEORY OF THE BALLOON. 37 following simple method. Three different kinds of colouredpapers are torn up into small pieces, the various papers havingdifferent thicknesses. Consequently each piece of paper beginsto fall at a particular rate, which is known by its colour. Forinstance, let us suppose that the white paper falls at the startwith a velocity of 18 in. per second, the blue a
Airships past and present, together with chapters on the use of balloons in connection with meteorology, photography and the carrier pigeon . Fig. 17.—The statoscope, byGradenwitz. 36 A1KSHIPS PAST AND THE THEORY OF THE BALLOON. 37 following simple method. Three different kinds of colouredpapers are torn up into small pieces, the various papers havingdifferent thicknesses. Consequently each piece of paper beginsto fall at a particular rate, which is known by its colour. Forinstance, let us suppose that the white paper falls at the startwith a velocity of 18 in. per second, the blue at the rate of 3 the red at the rate of 6 ft. per second. By throwing outa handful of these papers, it is possible to tell at once what isthe vertical movement. If the white pieces remain on a levelwith the balloon, then a fall is in progress at the rate of18 in. per second. If all the pieces rise above the balloon, thenthe descent is more rapid than 6 ft. per second; if they alldisappear below, then the balloon is either rising or at that the barometer shows an increase of pressure, andat the same time it is noticed that the white pieces of paperremain on a level with the car; it will
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