Page:Popular Science Monthly Volume 23.djvu/359

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THE GREAT BRIDGE AND ITS LESSONS.

origin of the work, or any complicity with fraud in its execution and completion. It is this consideration which induced me to accept the unexpected invitation of the trustees to speak for the city of New York on the present occasion. When they thus honored me, they did not know that John A. Roebling addressed to me the letter in which he first suggested (and, as far as I am aware, he was the first engineer to suggest) the feasibility of a bridge between the two cities, so constructed as to preserve unimpaired the freedom of navigation. This letter, dated June 19, 1857, I caused to be printed in the "Journal of Commerce," where it attracted great attention because it came from an engineer who had already demonstrated, by successfully building suspension bridges over the Schuylkill, the Ohio, and the Niagara Rivers, that he spoke with the voice of experience and authority. This letter was the first step toward the construction of the work, which, however, came about in a manner different from his expectations, and was finally completed on a plan more extensive than he had ventured to describe. It has been charged that the original estimates of cost have been far exceeded by the actual outlay. If this were true, the words of praise which I have uttered for the engineers who designed and executed this work ought rather to have been a sentence of censure and condemnation. Hence the invitation, which came to me unsought, seemed rather to be an appeal from the grave for such vindication as it was within my power to make, and which could not come with equal force from any other quarter.

Engineers are of two kinds—the creative and the constructive. The power to conceive great works demands imagination and faith. The creative engineer, like the poet, is born, not made. If to the power to conceive is added the ability to execute, then have we one of those rare geniuses who not only benefit the world but add new glory to humanity. Such men were Michael Angelo, Leonardo da Vinci, Watt, Wedgwood, Brunei, and Stephenson; and such a man was John A. Roebling. It was his striking peculiarity that, while his conceptions were bold and original, his execution was always exact and within the limits of cost which he assigned to the work of his brain. He had made bridges a study, and had declared in favor of the suspension principle for heavy traffic, when the greatest living authorities had condemned it as costly and unsafe. When he undertook to build a suspension-bridge for railway use, he did so in the face of the deliberate judgment of the profession, that success would be impossible. George Stephenson had condemned the suspension principle and approved the tubular girder for railway traffic. But it was the Nemesis of Stephenson's fate that, when he came out to approve the location of the great tubular bridge at Montreal, he should pass over the Niagara River in a railway-train, on a suspension-bridge, which he had declared to be an impracticable undertaking.

When Roebling suggested the bridge over the East River, his ideas