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 



