Engineer; born in
Lawrenceburg, Ind., May 23, 1820.
His controlling genius was manifested in early childhood.
His first invention was an apparatus for recovering vessels with their cargoes from the muddy depths of a river.
Eads made a fortune by it. In 1861 he was employed by the national government to construct gunboats, suitable for use in Western-rivers.
In the space of sixty-five days he constructed seven iron-clad gunboats.
In 1862 he built six more; also heavy mortar-boats.
These vessels performed mighty deeds during the
Civil War. At the beginning of July, 1874,
he completed a magnificent iron railroad bridge across the
Mississippi at
St. Louis, one of the finest structures of the kind in the world.
Then he pressed upon the attention of the government his plan for improving the navigation of the mouth of the
Mississippi by jetties.
He was authorized to undertake it (and was very successful), for which the government paid him $5,125,000. At the time of his death, in
Nassau, N. P., March 8, 1887, he was engaged in the promotion of a project he had conceived of constructing a ship railway across the Isthmus of Tehuantepec, between the
Atlantic and Pacific oceans.
In 1881 he received the
Albert medal from the British Society of Arts, the first American to be thus honored.
The jetty system consists simply of a dike or embankment projecting into the water, whose purpose is to narrow the channel so that the natural action of the water will keep it clear of sediment or other obstruction.
The
Mississippi River is, at its mouth, 40 feet deep and 1 3/4 miles wide, and carries every minute 72,000,000 feet of water to the
Gulf, which holds in solution nearly 20 per cent. of mud and sand.
The river has three channels to the sea—the
Southwest Pass, the Passe l'outre, and the
South Pass—the first carrying out about 50 per cent. of its water, the second 40 per cent., and the third 10 per cent. There is a bar at the mouth of each pass, and each has a channel through which large vessels may pass.
This channel is about 1,200 feet wide and 50 feet deep in the large passes, and 600 feet wide and 35 feet deep in the small one.
The swift and concentrated current keeps the channel open, but the bar is continually spreading outward, and as it thus spreads the water excavates a channel through it, though not of a uniform depth or width.
Thus, a frequent dredging of the channel was necessary to prevent the continual grounding of vessels upon it.
Captain Eads was the first to suggest that this laborious and expensive dredging process might be done away with by
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the use of jetties.
He reasoned that if the banks of the passage through the bar could be extended, not gradually, but immediately, into the deep water of the
Gulf some 2 miles or more, it would produce force enough to excavate a channel the whole length of the bar. This project he undertook to carry out at his own expense, agreeing not to receive compensation for the work until it was completed; and the truth of his reasoning was proved by the results.
In the winter of 1874-75 he laid his plan before Congress, and in March, 1875, a bill was passed empowering him to put it into execution.
The work was begun in June, 1875.
The jetties were lad out parallel with the current of the river, and at right angles with the
Gulf current, extending with a slight curve 2 1/4 miles out from the mouth of the river.
Piles were first driven in to mark the path of the jetties; then willows fastened together in enormous mattresses were sunk, and these filled in with stones and gravel.
This work was done on the
South Pass, the narrowest of the three channels of the
Mississippi delta.
Captain Eads wished to try his experiment on the
Southwest Pass, the deepest and widest channel, but Congress would not permit him to do so. The work of making the
South Pass jetties was completed July 9, 1879.
A channel 30 feet deep, with a minimum width of 45 feet, had been made from the river to deep water in the
Gulf. Five and a half million cubic yards of earth had been removed, mainly by the action of the strong current created by the jetty.
In the construction of this important improvement the following amount of material had been used: Willow, 592,000 cubic yards; stone, 100,000 cubic yards; gravel, 10,000 cubic yards; concrete, 9,000 tons; piling and lumber, 12,000,000 feet.
Captain Eads's plan has been proved to be very successful, for the banks of the jetty continue firm, and the channel is kept clear by the movement of the concentrated current between them.
