396 POPULAR SCIENCE MONTHLY, 



Tlie armored divers are mostly white sailors, Germans, Swedes, 

 a few Englisli, and an occasional American ; and so great is the 

 advantage of the diving suit that one armored diver is considered 

 equal to a whole crew of natives. Instead of a swift, breathless 

 struggle of fifty or sixty seconds, at a depth of fifty feet or less, 

 with a limit of seventy-five, the armored diver can work for ten 

 minutes at a depth of a hundred feet, while at a depth of thirty 

 he can work for a couple of hours. The deep-sea dangers to 

 which the naked diver is exposed are mostly shared by the ar- 

 mored diver. The protection from the tremendous crushing pres- 

 sure of the water afforded by the suit and the cushion of inclosed 

 air is offset by the increased pressure at greater depths. The 

 armored diver likewise encounters the venomous stonefish. This 

 little fish punctures the hand reaching for a shell and injects a 

 poison which causesthe whole arm to swell, with great pain. The 

 remedy is to remain down, as the pressure of water induces free 

 bleeding at the wound, and the consequent outflow of the poison. 

 If the bitten diver comes to the surface, as the unarmored diver 

 must, the arm swells rapidly, turns black, and is painful for weeks. 



Sharks do not attack the armored diver, but he has peculiar 

 perils which the naked native diver escapes. At some great depth 

 the air-pump may not work, or the air-pipe may burst. But there 

 are greater dangers yet. Pearl oysters are not found in beds, like 

 our edible bivalves, but scattered over the sea bottom ; hence it 

 is the custom to beat up against the tide or current, and then let 

 the lugger drift, with a drag-anchor perhaps. Yet sometimes the 

 drifting boat is seized by a strong current and whirled along, 

 and then, while the diver hurries on to keep up, his life-line or 

 air-pipe may become fatally entangled in branching coral ; or, 

 again, a slack line or pipe may fall into the jaws of the " giant 

 clam," which close over it, and hold the diver prisoner to his 

 death, alone in the dim ocean depths. 



The most perfect pearls are found within what is called " the 

 mantle " of the mollusk, an elastic membrane which envelops the 

 oyster, and which is supposed to secrete the nacreous fluid. The 

 finest specimens lie near the lips of the shell, or are imbedded in 

 the softer part of the oyster near the hinge of the shell. The 

 ideal gem pearl is spherical, white, without blemish in texture 

 or " skin,'' with pure " water " or appearance of transparency — 

 though no pearl is really transparent — and of distinguished lustre 

 or orient. Lustre is the soul of the pearl, as brilliancy is of the 

 diamond. Finely formed drop shapes, and then oval or egg 

 shapes, are but little below the spherical pearls in value, if of 

 equal perfection. The fine gem pearls are the size of peas ; very 

 much larger specimens, of twenty-five grains and upward, of per- 

 fect quality, are rare, and command corresponding values. 



