The professional reputation of the author of "The General Theory of Bridge-Construction" would of itself be a sufficient guaranty that a new work from the same source would be entitled to consideration. General Haupt does not often appear before the public as an author: his works are few, but of rare merit. The first which appeared, "The General Theory of Bridge-Construction," was the fruit of many years of experiment, observation, and calculation, and at once established his reputation in Europe and America, as unequalled in the specialty of Bridges. This work was not only the first, but up to the present time is the only publication in which the action of the parts in a complicated system is explained, and the direction and intensity of each and every strain brought within the reach of mathematical formulas, and rendered accurately determinable. Before the appearance of this book it is probable that not another engineer in the world could be found able to calculate the strain upon every sort of bridge-truss, but only on certain simple forms and combinations. Now, such calculations can be made by any student in any institution where civil engineering is taught thoroughly, and where "Haupt on Bridges" is used as a text-book. Professor Gillespie, writing from Europe, remarked that the greatest engineer of the age, Robert Stephenson, and his distinguished associates, had spoken of this book in terms of the highest commendation.
After the publication of the controversial papers between Messrs. Stephenson and Fairbairn in regard to the Britannia Bridge, it became apparent that neither of these gentlemen, with all their calculations and expenditures in experiments, had determined the proper distribution of the strains, and the size and strength required for the side-plates of tubular bridges, but only for those at the top and bottom. General Haupt solved the problem mathematically, and sent a communication on the subject to the American Association for the Advancement of Science, which has been extensively copied into the scientific journals of Europe, and has added largely to the reputation of its author. In the Victoria Bridge at Montreal, the distribution of material in the vertical plates conforms to the proportions given by General Haupt.
About the year 1853, General Haupt, then Chief Engineer of the Pennsylvania Railroad, reviewed the work of Charles Ellett on the Ohio and Mississippi Rivers, with other plans of improvement that had been suggested, and, in a pamphlet of about a hundred pages, proposed a novel, bold, and simple method for the improvement of these rivers, costing scarcely a tenth as much as the estimated expense of some of the other methods, and promising greater durability and efficacy. The Pittsburg Board of Trade recently appointed a scientific commission to investigate the whole subject; and their report, which is thorough and exhaustive, gives unanimously the preference to the plan of General Haupt, as the only practicable mode of improving the Ohio River, so as to insure a permanent depth of water of not less than six feet. In passing, we would remark that one of the greatest difficulties the War Department has had to contend with has been the lack of suitable navigation on the Ohio River, and it is to be regretted that Government did not at once seize upon the plans of General Haupt and carry them into execution.
In the spring of 1862, General Haupt was solicited to take charge of the reconstruction of the railroad from Acquia Creek to Fredericksburg. Without material other than that furnished by forests two miles distant, and without skilled mechanics, but simply by the aid of common soldiers who had no previous instruction, he erected, in nine days, a structure eighty feet high and four hundred feet long, which for more than a year carried the immense railroad-trains supplying the Army of the Potomac. It was visited and critically examined by officers in the foreign service, as a remarkable specimen of bold and successful military engineering.
Major-General McDowell, in his defence before the Court of Inquiry, made the following statement in regard to the Potomac-Creek Bridge, on the line of the Richmond, Fredericksburg, and Potomac Railroad.
"The large railroad-bridge over the Rappahannock, some six hundred feet long by sixty-five feet high, and the larger part of the one over Potomac Creek, some four hundred feet long by eighty feet high, were built from the trees cut down by the troops in the vicinity, and this without those troops losing their discipline or their instruction as soldiers. The work they did excited, to a high degree, the wonder and admiration of several distinguished foreign officers, who had never imagined such constructions possible by such means, and in such a way, in the time in which they were done.
"The Potomac-Run Bridge is a most remarkable structure. When it is considered, that, in the campaigns of Napoleon, trestle-bridges of more than one story, even of moderate height, were regarded as impracticable, and that, too, for common military roads, it is not difficult to understand why distinguished Europeans should express surprise at so bold a specimen of American military engineering. It is a structure which ignores all the rules and precedents of military science as laid down in books. It is constructed chiefly of round sticks cut from the woods, and not even divested of bark; the legs of the trestles are braced with round poles. It is in four stories, three of trestles and one of crib-work. The total height from the deepest part of the stream to the rail is nearly eighty feet. It carries daily from ten to twenty heavy railway-trains in both directions, and has withstood several severe freshets and storms without injury.
"This bridge was built in May, 1862, in nine working-days, during which time the greater part of the material was cut and hauled. It contains more than two million feet of lumber. The original structure, which it replaced, required as many months as this did days. It was constructed by the common soldiers of the Army of the Rappahannock, (command of Major-General McDowell,) under the supervision of his aide-de-camp, Colonel, now Brigadier-General, Hermann Haupt, Chief of Railroad Construction and Transportation."
A fine lithographic drawing of this bridge, taken from a photograph, forms the frontispiece to the volume before us.
Previous to the Battle of Chancellorsville, General Haupt received instructions to prepare for a rapid advance of the Army of the Potomac towards Richmond. He provided a sufficient amount of material to rebuild all the bridges between Fredericksburg and Richmond, and adopted the bold and novel expedient of portable railroad-bridge trusses. These trusses were built in advance, in spans of sixty feet; they were to be carried whole on cars to the end of the track, then dragged like logs, with the aid of timber-wheels and oxen, to the sites of the bridges, where they were to be raised bodily on wooden piers, and the rails laid over them. The reverse at Chancellorsville prevented this plan from being carried into effect; but four of these spans were used to replace the trestle-bridge across the Acquia Creek, where they were tested in actual use, and answered perfectly.