Experiments on Mr. Babbage's Method of Distinguishing Light-houses: Reported to a Committee of the United States Light-House Board
U.S. Government Printing Office, 1861 - Lighthouses - 116 pages
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according acid actual advantage allow already amount apparatus appear applied ascertained assumed average become boiler calculated carbonization cent characteristic circumstances column colza comparative comparison considered constant consumption containing corresponding count course cubic feet density determination direct distance distinction effect epitherm epochs equal examination existing Expansion experiments fact fixed flame former furnished further gave give given grains height identical illumination inch increase indicate instance intensity intervals lamp lard oil least less light light-house limit mass material mean measure mechanical method minute mixture natural nearly necessary observations obtained occultations period photometric possible pounds practical precision present pressure probable proper proportion quantity question ratio referred regard require respectively Robinson samples sound specific gravity sperm standard steam sufficient supposed taken temperature tion volume whale whole wick
Page 2 - it seems to be a natural consequence of the physical distribution of light that fixed lights which illuminate the whole horizon should be less powerful than revolving lights which have their effect concentrated within narrow sectors of the horizon.
Page 99 - itself was visible from where I stood, the deviation of the supposed