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 275
remained Constant throughout the year. But this has been shown to be altogetherwrong. There is eternal change even at great heights, and thetemperature varies just as much at levels of 30,000 ft. as at1,200 ft. Moreover, at the same heights above Paris and St.Petersburg there may be differences of… … SCIENTIFIC BALLOONING. 255 considerable differences of temperature. This layer-formationis one of the most important subjects at present underinvestigation. The future has still much work to do. At present, systematicobservations are made in few parts of the earth, and such portionsof our own…
Aeronautics
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