Abstract
WHERE a light on a rock or island has to illuminate constantly the whole horizon, the ordinary dioptric fixed apparatus is all that is required. But when, as at many places, there is a shoal at some distance from the llgfclhouse, or where a reef of rocks projects seawards from the shore, it sometimes becomes necessary to adopt means for keeping vessels clear of such dangers at night, as, for example, near Souter Point, where Mr. Douglass and Mr. J. T. Chance employed successfully the electric light for guarding a rock near the shore. What is wanted in such cases is to cover not only the danger itself but some area of the surrounding sea by a characteristic which is different from that of the main light.
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STEVENSON, T. New Modes of Showing Different Characteristics over Small Arcs in Azimuth from the same Light-House Apparatus . Nature 21, 156–157 (1879). https://doi.org/10.1038/021156b0
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DOI: https://doi.org/10.1038/021156b0