Part 2 (1/2)
Shortening them would of course have lowered the arch. Eads, who was just starting for London on financial business of the bridge, cut the tubes in half, joining them by a plug with a right and left screw. Then he cut off their ends, for the plug would make them any required length by inserting or withdrawing the screws a little. Then he went away. As it would have been much cheaper not to use this device, his a.s.sistants tried for hours to shrink the tubing by ice applications, and thus to get the arches closed; and there is a popular tradition in Saint Louis that they succeeded; but it was excessively hot weather, and they did not succeed. The screw-plug tubes, of course, were easily put in. Any part of this steel work can be at any time safely removed and replaced,--another structural feature original in this bridge.
Although Eads took care to protect his special innovations by patent, he was most willing to explain them with care to other engineers and to have others profit by his improvements; and several of the mechanical novelties of his bridge are now in the commonest use, and have been taken advantage of even in such famous structures as the Brooklyn Bridge.
During the building of the bridge Eads spent many months in enforced absence, but while in Europe he always had his labor in mind, and, as I have said, brought home from France one of his most useful appliances.
During his absence he left absolutely trustworthy and efficient engineers in charge of the work, and before leaving home he provided for accidents that might occur. So much work was done in the winter that great barriers had to be built to keep it clear of floating ice.
One curious detail connected with the bridge is that the Milwaukee, one of the double-turreted gunboats which Eads had built from his own plans, and which had been with Farragut at Mobile, was bought now from a wrecking company, and her iron hull used in making the caissons; so that her usefulness still continued in peace as in war.
It has been said of Eads that he grappled with great problems in engineering, and solved them as easily as a boy subtracts two from six.
While this is true, it must not be forgotten that he had not the school-training of an engineer. Nothing is more untrue than the statement that he was, like de Lesseps, only a contractor. He was a very unusually brilliant engineer, and his ignorance of the higher mathematics served to show his brilliancy the more clearly. Some persons have said that his chief talent was in explaining abstruse reasonings simply; but an engineer has told me that he thought Eads's chief talent was his ability to arrive by some rough means at a certain conclusion to a given problem, which conclusion would in every instance be approximately the same that better trained mathematicians would reach by mathematics.
By the time the bridge was finished, indeed from the time (1868) when his first report for it made a decided stir in the scientific world, both at home and abroad, Eads was a very well-known engineer. In that same year a visit to Europe for his health's sake gave him the opportunity to interview a French steel company, through whom he met a famous bridge-builder, and was led to examine the piers of the bridge then being constructed at Vichy; and it was there that he found his new ideas for caissons. Going home, by way of England, he explained his plans to the engineers there, and was by them proposed as a member of the Royal Society. Even at home, in his own adopted State, he was not without recognition; for in 1872 the University of Missouri conferred upon him the honorary degree of LL.D. From the general of engineers he received a request for suggestions for improvements in guns; and from his work on the subject of Naval Defenses it is plain that his mind still found time to run on this favorite topic.
In 1874 the bridge was finished. After it had satisfactorily stood the severe tests put upon it, it was formally opened on the 4th of July.
The celebrations of that day were the first public outburst of approval given to Eads's work. And to-day the strong and graceful bridge stands as his most beautiful and lasting monument. And as even the great tornado of 1896 was unable to do the piers any serious damage, they are likely to last indefinitely, and thus make the bridge ”endure,” as its builder said, ”as long as it is useful to man.”
To Saint Louis it has been so useful that while on the one hand the growth of the city was the cause of its being built, on the other it has been one great cause of the continued growth and prosperity of the city. But it had even broader results than that. ”It made a radical change in the conditions of transportation East and West, and it made possible the Memphis bridge and the future New Orleans bridge.”
And in another direction yet it is peculiarly important. In bridge-building it marks an era, not only because of its strength and beauty and the daring of its design, but also because of its many labor-saving devices, the inventions of a thoroughly practical mind. A distinguished engineer calls it ”a great pioneer in the art of sinking deep foundations and building spans over wide stretches of s.p.a.ce, that astonished in its construction the entire civilized world.” London ”Engineering” chose it, while building, as preeminently the ”most highly developed type of bridge;” and says, ”In that work the alliance between the theorist and the practical man is complete.” In Eads it finds its long-sighed-for dream, combining the highest powers of modern a.n.a.lysis with the ingenuity of the builder.
IV
THE JETTIES
The Mississippi River is a great antimonopolist. As more and more railways have been built it has been less and less used. And yet, because it drains almost every corner of a valley which comprises over one third of the whole United States, it affords means of transportation to an immense area; and since it cannot be controlled by any one company or group of companies, its freight rates can hardly be arbitrarily fixed. Still, so long as there are impediments to its free navigation in the shape of floods and bars, it cannot be depended on for s.h.i.+pping, and the magnificent opportunities it should offer to commerce are lessened. The vastest river system in the world, it shows in its various parts great contrasts. One large tributary flowing from the Alleghanies, one from the Rockies, one from the north, others from the southwestern plains, are each able to contribute their various products of grain, lumber, cattle, cotton, fruits, and so on. Some branches freeze every winter; others never do. Some are clear, others silt-bearing. From about Cairo it flows southward through the greater delta, or land built up by its own action in ages past, and in all this part of its course both banks and bottom are of yielding alluvion. For some hundreds of miles ”the crookedest of great rivers,” it varies frequently in width and velocity and is full of shoals; then for hundreds more, though uniform in width, it often rises higher than its sh.o.r.es, and is confined in artificial levees, which it continually breaks down. Finally, below New Orleans, growing more sluggish, and dividing into several mouths, or ”pa.s.ses,” it wanders through tracts of waste marsh-lands into the gulf, which it colors brown for miles around. Blocking the end of each shallow mouth there was formerly a sand-bar; and these obstructions to navigation were the despair of the river commerce, and no less the despair of the government in its attempts to remove them.
Every one interested in trade or s.h.i.+pping realized what a very serious hindrance to the usefulness of the Mississippi these choked-up mouths were, but no one realized it better than Eads. Understanding that the great valley is capable of supporting 400,000,000 people, and intent on doing all in his power for good, even before he had completed the bridge he was studying the problem of opening the river. Its improvement and the welfare of its millions of people were cherished objects of his life. For some men one great undertaking at a time is enough, but Eads's energies were such that his works overlapped one another. It is hard to see how one man can have time, even if he has brains, to do all he did. But apparently he never lived an idle day.
The bridge, with its many extraordinary solutions of new problems, made its builder's permanent reputation. At the particular request of West Point he had supplied that inst.i.tution with writings, diagrams, and models. And so far afield had his fame spread that on one of his many trips abroad, he made plans, at the request of the Sultan's grand vizier, for an iron bridge over the Bosphorus. A change in viziers, however, prevented its being built.
It seems as if the river-mouth problem had not always been so difficult. Still, Eads showed that the bars were inevitable; and it is probably only because, with the growing population and trade of the central States, the need for an outlet was greater, that the problem seemed more complicated. Moreover, ocean vessels were increasing in size and draught, which also made an adequate channel more desirable.
Although the blockade had forced the construction of several expensive lines of railway, yet it was impossible to carry all the products of the valley by rail. Millions of dollars' worth of merchandise were delayed at the bars. As early as 1726 attempts had been made to deepen the channels through the river's mouths by harrowing. But the first government effort was in 1837, when an appropriation was made for a survey and for dredging with buckets. Again in 1852 another appropriation was made; and a board, appointed by the War Department, recommended,--
1. Stirring up the bottom.
2. Dredging.
3. If both these methods failed, the construction of parallel jetties ”five miles in length, at the mouth of the South West Pa.s.s, to be extended into the gulf annually, as experience should show to be necessary.”
4. ”Should it then be needed, the lateral outlets should be closed.”
5. Should all these fail, a s.h.i.+p ca.n.a.l might be made.
Dredging by stirring the bottom was tried, and produced a depth of eighteen feet. Three years later this depth had entirely disappeared.
In 1856 an appropriation was entered into, but the jetties were never completed. Later than that dredging was tried again. Up to 1875 more than eighteen feet of depth had never been obtained, and even that could not be steadily preserved. Channels, opened in low water, were quickly filled up with sediment in high water, and sometimes a severe storm would wash in enough sand from the gulf to undo the result of months of dredging.
As early as 1832 a s.h.i.+p ca.n.a.l near Fort Saint Philip, which should cut through the river bank out to the gulf, had been planned, and this solution had been approved of by the Louisiana legislature. That idea had been revived from time to time. And there had also more than once been new recommendations made for jetties, which by narrowing the channel should deepen it. Finally Congress ordered surveys and plans for the ca.n.a.l, and then appointed a board not only to report on them, but also to ascertain the feasibility of improving the channel of one of the natural outlets of the river. In 1874 this board reported in favor of the ca.n.a.l, and against the idea of jetties, which, in its opinion, could hardly be built, could not be maintained, and would be excessively costly.
This, then, was the situation when Eads appeared on the scene: ”scratching and sc.r.a.ping” were going on in South West Pa.s.s, but were doing little real and no lasting good; the government engineers had declared themselves in favor of a ca.n.a.l; and though in some quarters jetties had been advocated, scarcely any one thought they could be built, or that if they were they would last, or that they would do any good. Eads, however, understood the river like a book, and he had studied this particular subject. He now came forward publicly, offering not only to build and to maintain jetties which would insure a twenty-eight foot channel, but to do all this for less than half the cost the board had estimated, and on a contract which should provide for his being paid only in case he succeeded. From this remarkable offer his own confidence in his plans may be inferred. A purpose which he had reasoned out as practical became an inspiration to him which nothing could shake, for his courage equaled his convictions.
But so bold was his proposition that he was considered a wild enthusiast. Never at a loss to solve any problem, again, as when he planned the bridge, he undertook to do what was commonly held to be impossible. Of course, all the backers of the ca.n.a.l scheme opposed him bitterly. New Orleans was of that faction. Saint Louis, on the other hand, upheld him because of his personal popularity and his signal success with the bridge. The army engineers were against him as a civil engineer. Thus the controversy was sectional, personal, and professional. Up to this time the government had invariably intrusted all works of river and harbor improvement to the military engineers; and to hand over the most important one it had ever undertaken to a private citizen, and to permit him to apply a method that had just been condemned in a report signed by six out of seven of the most distinguished army engineers, met with decided opposition. So the government hesitated. Certainly this was a proposal to make them consider, promising, as it did, an open river mouth, at a cost much lower than that of the ca.n.a.l, and in case of failure leaving the total loss to fall upon the contractor. Besides, several eminent civil engineers supported Eads's theory. The House, nevertheless, pa.s.sed the ca.n.a.l bill; but the Senate, more thorough, after calling Eads and two of his princ.i.p.al opponents to state their views before a committee, pa.s.sed a bill appointing a commission to reconsider the entire subject once more. The discussion before the Senate committee was one of the crises in Eads's life. The fate of the jetty enterprise hung on the outcome of it. Fortunately for himself and for the good of the country, he was a most magnetic and persuasive man. His theories and arguments were sound and logical, his experience of the river was vast; and beyond his apt.i.tude for making technical reasoning simple and clear, his skill as a diplomatist was equal to his ability as an engineer.