Boys' Second Book of Inventions

The famous Bug Light of Boston and Thimble Light of Hampton Roads, Va., are both good examples of the iron-pile lighthouse.

Now we come to a consideration of iron cylinder lighthouses, which are even more wonderful, perhaps, than the screw-piles, and in constructing them the sea-builder touches the pinnacle of his art.

Imagine a sandy shoal marked only by a white-fringed breaker. The water rushes over it in swift and constantly varying currents, and if there is a capful of wind anywhere on the sea, it becomes an instant menace to the mariner. The shore may be ten or twenty miles away, so far that a land-light would only lure the seaman into peril, instead of guiding him safely on his way. A lightship is always uncertain; the first great storm may drive it from its moorings and leave the coast unprotected when protection is most necessary. Upon such a shoal, often covered from ten to twenty feet with water, the builder is called upon to construct a lighthouse, laying his foundation in shifting sand, and placing upon it a building strong enough to withstand any storm or the crushing weight of wrecks or ice-packs.

It was less than twenty years ago that sea-builders first ventured to grapple with the difficulties presented by these off-shore shoals. In 1881 Germany built the first iron cylinder lighthouse at Rothersand, near the mouth of the Weser River, and three years later the Lighthouse Establishment of the United States planted a similar tower on Fourteen-Foot Banks, over three miles from the shores of Delaware Bay, in twenty feet of water. Since then many hitherto dangerous shoals have been marked by new lighthouses of this type.

When a builder begins a stone tower light on some lonely sea-rock, he says to the sea, "Do your worst. I'm going to stick right here until this light is built, if it takes a hundred years." And his men are always on hand in fair weather or foul, dropping one stone to-day and another to-morrow, and succeeding by virtue of steady grit and patience. The builder of the iron cylinder light pursues an exactly opposite course. His warfare is more spirited, more modern. He stakes his whole success on a single desperate throw. If he fails, he loses everything: if he wins, he may throw again. His lighthouse is built, from foundation caisson to lantern, a hundred or a thousand miles away from the reef where it is finally to rest. It is simply an enormous cast-iron tube made in sections or courses, each about six feet high, not unlike the standpipe of a village water-works. The builder must set up this tube on the shoal, sink it deep into the sand bottom, and fill it with rocks and concrete mortar, so that it will not tip over. At first such a feat would seem absolutely impossible; but the sea-builder has his own methods of fighting. With all the material necessary to his work, he creeps up on the shoal and lies quietly in some secluded harbour until the sea is calmly at rest, suspecting no attack. Then he darts out with his whole fleet, plants his foundation, and before the waves and the wind wake up he has established his outworks on the shoal. The story of the construction of one of these lighthouses will give a good idea of the terrible difficulties which their builders must overcome.

Not long ago W. H. Flaherty, of New York, built such a lighthouse at Smith's Point, in Chesapeake Bay. At the mouth of the Potomac River the opposing tides and currents have built up shoals of sand extending eight or ten miles out into the bay. Here the waves, sweeping in from the open Atlantic, sometimes drown the side-lights of the big Boston steamers. The point has a grim story of wrecks and loss of life; in 1897 alone, four sea-craft were driven in and swamped on the shoals. The Lighthouse Establishment planned to set up the light just at the edge of the channel, and 120 miles south of Baltimore.

Eighty thousand dollars was appropriated for doing the work. In August, 1896, the contractors formally agreed to build the lighthouse for $56,000, and, more than that, to have the lantern burning within a single year.

By the last of September a huge, unwieldy foundation caisson was framing in a Baltimore shipyard. This caisson was a bottomless wooden box, 32 feet square and 12 feet high, with the top nearly as thick as the height of a man, so that it would easily sustain the weight of the great iron cylinder soon to be placed upon it. It was lined and caulked, painted inside and out to make it air-tight and water-tight, and then dragged out into the bay, together with half an acre of mud and dock timbers. Here the workmen crowned it with the first two courses of the iron cylinder – a collar 30 feet in diameter and about 12 feet high. Inside of this a second cylinder, a steel air-shaft, five feet in diameter, rose from a hole in the centre of the caisson, this providing a means of entrance and exit when the structure should reach the shoal.

Upon the addition of this vast weight of iron and steel, the wooden caisson, although it weighed nearly a hundred tons, disappeared completely under the water, leaving in view only the great black rim of the iron cylinder and the top of the air-shaft.

On April 7th of the next year the fleet was ready to start on its voyage of conquest. The whole country had contributed to the expedition. Cleveland, O., furnished the iron plates for the tower; Pittsburg sent steel and machinery; South Carolina supplied the enormous yellow-pine timbers for the caisson; Washington provided two great barge-loads of stone; and New York City contributed hundreds of tons of Portland cement and sand and gravel, it being cheaper to bring even such supplies from the North than to gather them on the shores of the bay.

Everything necessary to the completion of the lighthouse and the maintenance of the eighty-eight men was loaded aboard ship. And quite a fleet it made as it lay out on the bay in the warm spring sunshine. The flagship was a big, double-deck steamer, 200 feet over all, once used in the coastwise trade. She was loaded close down to her white lines, and men lay over her rails in double rows. She led the fleet down the bay, and two tugs and seven barges followed in her wake like a flock of ducklings. The steamer towed the caisson at the end of a long hawser.

In three days the fleet reached the lighthouse site. During all of this time the sea had been calm, with only occasional puffs of wind, and the builders planned, somewhat exultantly, to drop the caisson the moment they arrived.

But before they were well in sight of the point, the sea awakened suddenly, as if conscious of the planned surprise. A storm blew up in the north, and at sunset on the tenth of April the waves were washing over the top of the iron cylinder and slapping it about like a boy's raft. A few tons of water inside the structure would sink it entirely, and the builder would lose months of work and thousands of dollars.

From a rude platform on top of the cylinder two men were working at the pumps to keep the water out. When the edge of the great iron rim heaved up with the waves, they pumped and shouted; and when it went down, they strangled and clung for their lives.

The builder saw the necessity of immediate assistance. Twelve men scrambled into a life-boat, and three waves later they were dashed against the rim of the cylinder. Here half of the number, clinging like cats to the iron plates, spread out a sail canvas and drew it over the windward half of the cylinder, while the other men pulled it down with their hands and teeth and lashed it firmly into place. In this way the cylinder shed most of the wash, although the larger waves still scuttled down within its iron sides. Half of the crew was now hurried down the rope-ladders inside the cylinder, where the water was nearly three feet deep and swashing about like a whirlpool. They all knew that one more than ordinarily large wave would send the whole structure to the bottom; but they dipped swiftly, and passed up the water without a word. It was nothing short of a battle for life. They must keep the water down, or drown like rats in a hole. They began work at sunset, and at sunrise the next morning, when the fury of the storm was somewhat abated, they were still at work, and the cylinder was saved.

The swells were now too high to think of planting the caisson, and the fleet ran into the mouth of the Great Wicomico River to await a more favourable opportunity. Here the builders lay for a week. To keep the men busy some of them were employed in mixing concrete, adding another course of iron to the cylinder, and in other tasks of preparation. The crew was composed largely of Americans and Irishmen, with a few Norwegians, the ordinary Italian or Bohemian labourer not taking kindly to the risks and terrors of such an expedition. Their number included carpenters, masons, iron-workers, bricklayers, caisson-men, sailors, and a host of common shovellers. The pay varied from twenty to fifty cents an hour for time actually worked, and the builders furnished meals of unlimited ham, bread, and coffee.

On April 17th, the weather being calmer, the fleet ventured out stealthily. A buoy marked the spot where the lighthouse was to stand. When the cylinder was exactly over the chosen site, the valves of two of the compartments into which it was divided were quickly opened, and the water poured in. The moment the lower edge of the caisson, borne downward by the weight of water, touched the shoal, the men began working with feverish haste. Large stones were rolled from the barges around the outside of the caisson to prevent the water from eating away the sand and tipping the structure over.

In the meantime a crew of twenty men had taken their places in the compartments of the cylinder still unfilled with water. A chute from the steamer vomited a steady stream of dusty concrete down upon their heads. A pump drenched them with an unceasing cataract of salt water. In this terrible hole they wallowed and struggled, shovelling the concrete mortar into place and ramming it down. Every man on the expedition, even the cooks and the stokers, was called upon at this supreme moment to take part in the work. Unless the structure could be sufficiently ballasted while the water was calm, the first wave would brush it over and pound it to pieces on the shoals.

After nearly two hours of this exhausting labour the captain of the steamer suddenly shouted the command to cast away.

The sky had turned black and the waves ran high. All of the cranes were whipped in, and up from the cylinder poured the shovellers, looking as if they had been freshly rolled in a mortar bed. There was a confused babel of voices and a wild flight for the steamer. In the midst of the excitement one of the barges snapped a hawser, and, being lightened of its load, it all but turned over in a trough of the sea. The men aboard her went down on their faces, clung fast, and shouted for help, and it was only with difficulty that they were rescued. One of the life-boats, venturing too near the iron cylinder, was crushed like an egg-shell, but a tug was ready to pick up the men who manned it.

So terrified were the workmen by the dangers and difficulties of the task that twelve of them ran away that night without asking for their pay.

On the following morning the builder was appalled to see that the cylinder was inclined more than four feet from the perpendicular. In spite of the stone piled around the caisson, the water had washed the sand from under one edge of it, and it had tipped part way over. Now was the pivotal point of the whole enterprise. A little lack of courage or skill, and the work was doomed.

The waves still ran high, and the freshet currents from the Potomac River poured past the shoals at the rate of six or seven miles an hour. And yet one of the tugs ran out daringly, dragging a barge-load of stone. It was made fast, and although it pitched up and down so that every wave threatened to swamp it and every man aboard was seasick, they managed to throw off 200 tons more of stone around the base of the caisson on the side toward which it was inclined. In this way further tipping in that direction was prevented, and the action of the water on the sand under the opposite side soon righted the structure.

Beginning on the morning of April 21st the entire crew worked steadily for forty-eight hours without sleeping or stopping for meals more than fifteen minutes at a time. When at last they were relieved, they came up out of the cylinder shouting and cheering because the foundation was at last secure.

The structure was now about thirty feet high, and filled nearly to the top with concrete. The next step was to force it down 15½ feet into the hard sand at the bottom of the bay, thus securing it for ever against the power of the waves and the tide. An air-lock, which is a strongly built steel chamber about the size of a hogshead, was placed on top of the air-shaft, the water in the big box-like caisson at the bottom of the cylinder was forced out with compressed air, and the men prepared to enter the caisson.

No toil can compare in its severity and danger with that of a caisson worker. He is first sent into the air-lock, and the air-pressure is gradually increased around him until it equals that of the caisson below; then he may descend. New men often shout and beg pitifully to be liberated from the torture. Frequently the effect of the compressed air is such that they bleed at the ears and nose, and for a time their heads throb as if about to burst open.

In a few minutes these pains pass away, the workers crawl down the long ladder of the air-shaft and begin to dig away the sand of the sea-bottom. It is heaped high around the bottom of a four-inch pipe which leads up the air-shaft and reaches out over the sea. A valve in the pipe is opened and the sand and stones are driven upward by the compressed air in the caisson and blown out into the water with tremendous force. As the sand is mined away, the great tower above it slowly sinks downward, while the subterranean toilers grow sallow-faced, yellow-eyed, become half deaf, and lose their appetites.

When Smith's Point Light was within two feet of being deep enough the workmen had a strange and terrible adventure.

Ten men were in the caisson at the time. They noticed that the candles stuck along the wall were burning a lambent green. Black streaks, that widened swiftly, formed along the white-painted walls. One man after another began staggering dizzily, with eyes blinded and a sharp burning in the throat. Orders were instantly given to ascend, and the crew, with the help of ropes, succeeded in escaping. All that night the men lay moaning and sleepless in their bunks. In the morning only a few of them could open their eyes, and all experienced the keenest torture in the presence of light. Bags were fitted over their heads, and they were led out to their meals.

That afternoon Major E. H. Ruffner, of Baltimore, the Government engineer for the district, appeared with two physicians. An examination of the caisson showed that the men had struck a vein of sulphuretted hydrogen gas.

Here was a new difficulty – a difficulty never before encountered in lighthouse construction. For three days the force lay idle. There seemed no way of completing the foundation. On the fourth day, after another flooding of the caisson, Mr. Flaherty called for volunteers to go down the air-shaft, agreeing to accompany them himself – all this in the face of the spectacle of thirty-five men moaning in their bunks, with their eyes burning and blinded and their throats raw. And yet fourteen men stepped forward and offered to "see the work through."

Upon reaching the bottom of the tower they found that the flow of gas was less rapid, and they worked with almost frantic energy, expecting every moment to feel the gas griping in their throats. In half an hour another shift came on, and before night the lighthouse was within an inch or two of its final resting-place.

The last shift was headed by an old caisson-man named Griffin, who bore the record of having stood seventy-five pounds of air-pressure in the famous Long Island gas tunnel. Just as the men were ready to leave the caisson the gas suddenly burst up again with something of explosive violence. Instantly the workmen threw down their tools and made a dash for the air-shaft. Here a terrible struggle followed. Only one man could go up the ladder at a time, and they scrambled and fought, pulling down by main force every man who succeeded in reaching the rounds. Then one after another they dropped in the sand, unconscious.

Griffin, remaining below, had signalled for a rope. When it came down, he groped for the nearest workman, fastened it around his body, and sent him aloft. Then he crawled around and pulled the unconscious workmen together under the air-shaft. One by one he sent them up. The last was a powerfully built Irishman named Howard. Griffin's eyes were blinded, and he was so dizzy that he reeled like a drunken man, but he managed to get the rope around Howard's body and start him up. At the eighteen-inch door of the lock the unconscious Irishman wedged fast, and those outside could not pull him through. Griffin climbed painfully up the thirty feet of ladder and pushed and pulled until Howard's limp body went through. Griffin tried to follow him, but his numbed fingers slipped on the steel rim, and he fell backward into the death-hole below. They dropped the rope again, but there was no response. One of the men called Griffin by name. The half-conscious caisson-man aroused himself and managed to tie the rope under his arms. Then he, too, was hoisted aloft, and when he was dragged from the caisson, more dead than alive, the half-blinded men on the steamer's deck set up a shout of applause – all the credit that he ever received.

Two of the men prostrated by the gas were sent to a hospital in New York, where they were months in recovering. Another went insane. Griffin was blind for three weeks. Four other caisson-men came out of the work with the painful malady known as "bends," which attacks those who work long under high air-pressure. A victim of the "bends" cannot straighten his back, and often his legs and arms are cramped and contorted. These terrible results will give a good idea of the heroism required of the sea-builder.

Having sunk the caisson deep enough the workmen filled it full of concrete and sealed the top of the air-shaft. Then they built the light-keeper's home, and the lantern was ready for lighting. Three days within the contract year the tower was formally turned over to the Government.

And thus the builders, besides providing a warning to the hundreds of vessels that yearly pass up the bay, erected a lasting monument to their own skill, courage, and perseverance. As long as the shoal remains the light will stand. In the course of half a century, perhaps less, the sea-water will gnaw away the iron of the cylinder, but there will still remain the core of concrete, as hard and solid as the day on which it was planted.

It is fitting that work which has drawn so largely upon the highest intellectual and moral endowments of the engineer and the builder should not serve the selfish interests of any one man, nor of any single corporation, nor even of the Government which provided the means, but that it should be a gift to the world at large. Other nations, even Great Britain, which has more at stake upon the seas than any other country, impose regular lighthouse taxes upon vessels entering their harbours; but the lights erected by the United States flash a free warning to any ship of any land.