. About lobsters. Lobsters; Lobster fisheries. 84 ABOUT LOBSTERS not seem to be the answer, as poor fishing occurs dur- * * ing high tides even when the moon is obscured. Recently, during a five-year period, one investigator tried every combination of lights that he could devise. Here are some of the schemes: First, he worked largely with real radium salts such as are painted on watch dials; also Willemite, a zinc material which glows brilliant green under the influence of radium radiations. Another chemical tested was a phosphorus com- pound and zinc cadmium sulphite. His best mounting of rad
. About lobsters. Lobsters; Lobster fisheries. 84 ABOUT LOBSTERS not seem to be the answer, as poor fishing occurs dur- * * ing high tides even when the moon is obscured. Recently, during a five-year period, one investigator tried every combination of lights that he could devise. Here are some of the schemes: First, he worked largely with real radium salts such as are painted on watch dials; also Willemite, a zinc material which glows brilliant green under the influence of radium radiations. Another chemical tested was a phosphorus com- pound and zinc cadmium sulphite. His best mounting of radium was inside the ball-like glass top of a coffee percola- tor. This glass could be plugged with a rubber cork, making it watertight (see Figure 15). This device was tried in various degrees of brightness be- cause it was feared that the light might be too bright for the light- sensitive eyes of a lobster in twenty fathoms of water, where there is normally almost no light. Tests were attempted in the usual lob- ster tanks in a very dark room, at first, but this investigator had no confidence in them since he knew, as do lobstermen, that lobsters act very differently in a tank than they do on the ocean floor. All tests thereafter were made in pots under actual fishing conditions, and a careful record was kept. Several skin-diving photographers have reported that sea water absorbs red light rays completely at 30 feet deep —as it also does yellow and orange—in fact, at over 90 feet deep, all things become a monotonous blue-grey. Artificial light, however, shows up all the true colors, hence those highly colored photographs taken with flash bulbs. Many tests were made, covering the glass knob with different colored cellophane. Cellophane was used because it would not disintegrate in water, and because different. Fig. 15. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of thes
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Keywords: ., bookcentury1900, bookcollectionbiod, booksubjectlobsterfisheries
