Airships past and present, together with chapters on the use of balloons in connection with meteorology, photography and the carrier pigeon (1908)
Hildebrandt, A. (Alfred), b. 1870, Story, W. H. tr · New York, D. Van Nostrand company · leaf 321
hers, andtherefore all bright objects appear redder and consequentlydarker on the plate. An effect of absorption and reflection isthat all the bright colours are, as it were, displaced towards thered end of the spectrum and the darker colours appear bluer.It is therefore necessary to supplement the… … Fig. 187.—Photograph of a village, taken at night, by means oE an electricprojector, by the Vega Company of Geneva. restrained in order that they may appear darker on the plate.Yellow filters can therefore be used in a good light, because thetime of exposure in a balloon can generally be reduced.…
Aeronautics
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