THE IMPENETRABLE SEA 



powerful ones using cartridges. Some of these fire fifty or 

 sixty shots from a magazine. 



Spear-points may be explosive. One type, the Bel- 

 Aqua Thunderhead is an impact powder-head which 

 enables the user to kill big fish. There are also many 

 kinds of knives, and a variety of gloves. Many diving 

 spearmen wear only one glove — on the hand not used for 

 firing the gun. Some gloves are not merely protective 

 but webbed, serving a double purpose: enabling the 

 wearer to hold on to coral, or grab a poisonous fish, 

 and also giving him a little extra speed through the 

 water. 



Special waterproof flashlights are used for night diving. 

 There are underwater compasses specially made for 

 divers, with luminous dials; spectacle frames for divers 

 with poor sight, which fit inside the masks; waterproof 

 watches; and even underwater scooters! These are 

 strapped to the body and have paddles operated by the 

 feet. They are said to increase the diver's underwater 

 speed by as much as three hundred per cent. 



Underwater cameras have reached a high degree of 

 perfection. There are now, in many countries, some 

 thousands of underwater photographers, from amateurs 

 using Brownies in football-bladders to professional movie 

 cameramen using hundreds of miles of film a year as they 

 record the habits of sea creatures and the adventures of 

 the divers who are investigating them. 



Weighted belts are sometimes used to facilitate faster 

 and deeper descents, even by divers operating without 

 self-contained oxygen appliances. These are so devised 

 that they can be released instantly in emergencies. 

 Fathometers are now available in many sporting goods 

 stores. The appliance is strapped to the knee, and registers 

 the depth of the diver. For those on the surface, watching 

 the diver as he goes down, there are many new inven- 

 tions, including waterscopes (developed from the old- 

 fashioned glass-bottomed boxes used by the natives) 



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