For general usefulness and practicability to the collector, nothing seems 

 to surpass the skin-diving system. There is, however, another device, the 

 diving-helmet, which offers certain advantages. Because of the helmet's 

 constant supply of fresh air, pumped down from the surface, a diver is per- 

 mitted to roam about leisurely and in comparative comfort at greater depths 

 than is possible with goggles. For purposes of observation the helmet is 

 almost ideal. The collector has ample opportunity to watch for the tell- 

 tale movement as the large Pecten and Spondylus, ordinarily so covered 

 with algae a, to be unrecognizable, snap their valves closed. He may also 

 gather large sacks of sponge and other material to be sent to the surface 

 and later examined for living minutia. In fairness, we must admit certain 

 disadvantages for this manner of collecting. The associated gear is neces- 

 sarily bulky and expensive. On the bottom the diver finds movement 

 clumsy and awkward, for the helmet must always be maintained in a nearly 

 upright position to prevent the precious supply of air from escaping. Also, 

 helmet diving is not entirely without an element of danger. Contrary to 

 popular belief, few divers are lost because of attacks by undersea creatures; 

 most are lost because of defects in diving mechanism which throws a sudden 

 strain on the human system, a system never designed for such abuse. 



We shall not attempt to discuss here the effects of pressure upon the 

 human organism but suffice it to say that present-day man is poorly adapt- 

 ed to withstanding any considerable or sudden changes of air pressure. 

 This same air pressure, so necessary to counteract the crushing weight of 

 the water, is always the diver's greatest fear, for with it come the dreaded 

 "bends." Fortunately, the shell collector is unlikely to be diving at a depth 

 greater than 35 feet and may disregard the worries about decompression to 

 prevent the occurrence of this crippling malady. Make no mistake, how- 

 ever, for the pressures encountered in helmet-diving at depths no more than 

 20 or 30 feet are potentially dangerous. It is important that a novice fully 

 realize this fact and exercise every precaution to avoid trouble. Rule 

 number one should be: Never leave the helmet while it is under water. 

 The United States Naval school of diving considers a rise of only 7 feet to 

 the surface, when the lungs are filled with air pressure, as being dangerous 

 to human life. When you go down or come up from a dive, do so slowly 

 and continue regular breathing at all times. Never hold the breath while 

 ascending, even though the air in your helmet may seem foul. Rule num- 

 ber two should be: Move slowly while under water. Any unusual exertion 

 brings undue fatigue and the diver must always have sufficient energy in 

 reserve to cope with problems that cannot be anticipated. Observe the e 

 simple rules and you will be safer in a diving-helmet than you would be 

 while crossing a busy city street. 



Perhaps some AMU members have yet to make their first dive, and 

 are curious to know something about what one sees and does below, be- 

 fore making the venture. Let us go on an imaginary diving trip together. 



For our first dive let's explore the wreck of an old schooner which lies 

 in 30 feet of water along the edge of a Florida coral reef. You are probably 

 amazed at the various assortment of gear which is needed for the diving 



(32) 



