The air which sustains the diver’s life below the surface is pumped from above by a powerful pump, which must be kept constantly at work while the diver is down. A stoppage of the pump a single instant while the diver is in deep water would result almost in his instant death from the pressure of the water outside. The greatest depth reached by any diver was 204 feet, at which depth there was a pressure of 88¹⁄₂ pounds per square inch on his body. The area exposed of the average diver in armor is 720 inches, which would have made the diver at that depth sustain a pressure of 66,960 pounds, or over 33 tons. The water pressure on a diver is as follows: 20 feet 8¹⁄₂ lbs. 30 feet 12³⁄₄ lbs. 40 feet 17¹⁄₄ lbs. 50 feet 21³⁄₄ lbs. 60 feet 26¹⁄₄ lbs. 70 feet 30¹⁄₂ lbs. 80 feet 34³⁄₄ lbs. 90 feet 39 lbs. 100 feet 43¹⁄₂ lbs. 120 feet 52¹⁄₄ lbs. 130 feet 56¹⁄₂ lbs. 140 feet 60³⁄₄ lbs. 150 feet 65¹⁄₄ lbs. 160 feet 69³⁄₄ lbs. 170 feet 74 lbs. 180 feet 78 lbs. 190 feet 82¹⁄₄ lbs. 204 feet 88¹⁄₂ lbs. The dangers of diving are manifold, and so risky is the calling that there are comparatively few divers in the United States. The cheapest of them command $10.00 a day for four or five hours’ work, and many of them get $50.00 and $60.00 for the same term of labor under water. The greatest danger that besets the diver is the risk he runs every time he dives of rupturing a blood-vessel by the excessively compressed air he is compelled to breathe. He is also subject to attacks from sharks, sword-fish, devil-fish, and other voracious monsters of the ocean’s depths. To defend himself against them, he carries a double-edged knife as sharp as a razor. It is the diver’s sole weapon of defense. Just how far back the art of submarine diving dates is a matter of conjecture, but until the invention of the present armor and helmet, in 1839, work and exploration under water was, at best, imperfect, and could only be pursued in a very limited degree. Feats of Divers. ~THE GREATEST DIVING FEAT~ Millions of dollars’ worth of property has been recovered from the ocean’s depth by divers. One of the greatest achievements in this line was by the famous English diver, Lambert, who recovered vast treasure from the “Alfonso XII,” a Spanish mail steamer belonging to the Lopez Line, which sank off Point Gando, Grand Canary, in 26¹⁄₂ fathoms of water. The salvage party was dispatched by the underwriters in May, 1885, the vessel having £100,000 in specie on board. For nearly six months the operations were persevered in before the divers could reach the treasure-room beneath the three decks. Two divers lost their lives in the vain attempt, the pressure of water being fatal. The diver recovered £90,000 from the wreck, and got £4,500 for doing it.