Part 47

This enables the diver to talk at all times to those above him.]

It is made of tinned copper, with three glass-covered openings, to enable the diver to look out.]

TESTING THE TELEPHONE.

Every precaution is taken to see that everything is in order before the diver goes down.]

The least error in the adjustment may mean death to the diver.]

The helmet is made of tinned copper, with three circular glasses, one in front and one on either side, with guards to protect them. The front eye-piece is made to unscrew and enable the diver to receive or give instructions without removing the helmet. One or more outlet valves are placed at the back or side of the helmet to allow the vitiated air to escape. These valves only open outwards by working against a spiral spring, so that no water can enter. The inlet valve is at the back of the helmet, and the air on entry is directed by three channels running along the top of the helmet to points above the eye-pieces, enabling the diver to always inhale fresh air. The helmet is secured to the breastplate below by a segmental screw-bayonet joint, securing attachment by one-eighth of a turn. The junction between the water-proof dress and the breastplate is made watertight by means of studs, brass plates and wing-nuts.

A life or signal-line and also a modern telephone enables the diver to communicate at all times with those above him.

The cost of a complete diving outfit ranges from $750.00 to $1,000.00. The weight of the armor and attachments worn by the diver is 256 pounds, divided as follows: Helmet and breastplate, 58 pounds; belt of lead weights, 122 pounds; rubber suit, 19 pounds; iron-soled shoes, 27 pounds each.

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.

One of the most difficult operations ever performed by a diver was the recovering of the treasure sunk in the steamship “Malabar,” off Galle. On this occasion the large iron plates, half an inch thick, had to be cut away from the mail-room, and then the diver had to work through nine feet of sand. The whole of the specie on board this vessel--upward of $1,500,000--was saved, as much as $80,000 having been gotten out in one day.

It is an interesting fact that from time to time expeditions have been fitted out, and companies formed, with the sole intention of searching for buried treasure beneath the sea. Again and again have expeditions left New York or San Francisco in the certainty of recovering tons of bullion sunk off the Brazilian coast, or lying undisturbed in the mud of the Rio de la Plata.

At the end of 1885, the large steamer Imbus, belonging to the P. & O. Co., sank off Trincomalee, having on board a very valuable East-India cargo, together with a large amount of specie. This was another case of a fortune found in the sea, for a very large amount of treasure was recovered.

Another wreck from which a large sum of gold coin and bullion was recovered by divers, was that of the French ship “L’Orient.” She is stated to have had on board specie to the value of no less than $3,000,000, besides other treasure.

A parallel case to “L’Orient” is that of the “Lutine,” a warship of thirty-two guns, wrecked off the coast of Holland. This vessel sailed from the Yarmouth Roads with an immense quantity of treasure for the Texel. In the course of the day it came on to blow a heavy gale; the vessel was lost and went to pieces. Salvage operations by divers, during eighteen months, resulted in the recovery of £400,000 in specie.

Humorous scenes do not play much of a part on the ocean’s bottom, and the sublime and awe-inspiring are far more in evidence there than the ludicrous, yet even beneath the waves there are laughable scenes at times. A diver had been engaged to inspect a sunken vessel off the coast of Cuba. Arriving on the scene he discovered a number of native sponge-divers, who descend to considerable depths, diving down from their canoes to the sunken vessel trying to pick up something of value. They paid little attention to the arrival of the wrecking outfit, and did not notice the diver descend, until suddenly what seemed to them to be a horrible human-shaped monster, with an immense head of glistening copper and three big, round, glassy eyes, came walking around the vessel’s bow and made a big salaam to them. That was enough. They shot surfaceward like sky-rockets, climbed frantically into their canoes and hurriedly rowed away.

What Happens When Anything Explodes?

By explosives are meant substances that can be made to give off a large quantity of gas in an exceedingly short time, and the shorter the time required for the production of the gas the greater will be the violence of the explosion. Many substances that ordinarily have no explosive qualities may be made to act as explosives under certain circumstances. Water, for example, has caused very destructive boiler explosions when a quantity of it has been allowed to enter an empty boiler that had become red hot. Particles of dust in the air have occasioned explosions in saw mills, where the air always contains large quantities of dust. A flame introduced into air that is heavily laden with dust may cause a sudden burning of the particles near it, and from these the fire may be conveyed so rapidly to the others that the heat will cause the air to expand suddenly, and this, together with the formation of gases from the burning, will cause an explosion.

It must not be thought, however, that fine sawdust or water would ordinarily be classed as explosives. The term is generally applied only to those substances that may be very easily caused to explode.

The oldest, and most widely known, explosive that we possess is gunpowder, the invention of which is generally credited to the Chinese. It is a mixture of potassium nitrate, or saltpeter, with powdered charcoal and sulphur. The proportions in which these substances are mixed vary in different kinds of powder, but they usually do not differ much from the following: