Harper's New Monthly Magazine, Vol. 3, July, 1851

by Various

In Mr. Francis's presses, the dies between which the sheets of iron or copper are pressed; are directly above the four cylinders which we have described, as will be seen by referring once more to the drawing. The upper die is fixed—being firmly attached to the top of the frame, and held securely down by the rows of iron pillars on the two sides, and by the massive iron caps, called platens, which may be seen passing across at the top, from pillar to pillar. These caps are held by large iron nuts which are screwed down over the ends of the pillars above. The lower die is movable. It is attached by massive iron work to the ends of the piston-rods, and of course it rises when the pistons are driven upward by the pressure of the water. The plate of metal, when the dies approach each other, is bent and drawn into the intended shape by the force of the pressure, receiving not only the corrugations which are designed to stiffen it, but also the general shaping necessary, in respect to swell and curvature, to give it the proper form for the side, or the portion of a side, of a boat.

It is obviously necessary that these dies should fit each other in a very accurate manner, so as to compress the iron equally in every part. To make them fit thus exactly, massive as they are in magnitude, and irregular in form, is a work of immense labor. They are first cast as nearly as possible to the form intended, but as such castings always warp more or less in cooling, there is a great deal of fitting afterward required, to make them come rightly together. This could easily be done by machinery if the surfaces were square, or cylindrical, or of any other mathematical form to which the working of machinery could be adapted. But the curved and winding surfaces which form the hull of a boat or vessel, smooth and flowing as they are, and controlled, too, by established and well-known laws, bid defiance to all the attempts of mere mechanical motion to follow them. The superfluous iron, therefore, of these dies, must all be cut away by chisels driven by a hammer held in the hand; and so great is the labor required to fit and smooth and polish them, that a pair of them costs several thousand dollars before they are completed and ready to fulfill their function.

The superiority of metallic boats, whether of copper or iron, made in the manner above described, over those of any other construction, is growing every year more and more apparent. They are more light and more easily managed, they require far less repair from year to year, and are very much longer lived. When iron is used for this purpose, a preparation is employed that is called galvanized iron. This manufacture consists of plates of iron of the requisite thickness, coated on each side, first with tin, and then with zinc; the tin being used simply as a solder, to unite the other metals. The plate presents, therefore, to the water, only a surface of zinc, which resists all action, so that the boats thus made are subject to no species of decay. They can be injured or destroyed only by violence, and even violence acts at a very great disadvantage in attacking them. The stroke of a shot, or a concussion of any kind that would split or shiver a wooden boat so as to damage it past repair, would only indent, or at most perforate, an iron one. And a perforation even, when made, is very easily repaired, even by the navigators themselves, under circumstances however unfavorable. With a smooth and heavy stone placed upon the outside for an anvil, and another used on the inside as a hammer, the protrusion is easily beaten down, the opening is closed, the continuity of surface is restored, and the damaged boat becomes, excepting, perhaps, in the imagination of the navigator, as good once more as ever.

Metallic boats of this character were employed by the party under Lieut. Lynch, in making, some years ago, their celebrated voyage down the river Jordan to the Dead Sea. The navigation of this stream was difficult and perilous in the highest degree. The boats were subject to the severest possible tests and trials. They were impelled against rocks, they were dragged over shoals, they were swept down cataracts and cascades. There was one wooden boat in the little squadron; but this was soon so strained and battered that it could no longer be kept afloat, and it was abandoned. The metallic boats, however, lived through the whole, and finally floated in peace on the heavy waters of the Dead Sea, in nearly as good a condition as when they first came from Mr. Francis's dies.

The seams of a metallic boat will never open by exposure to the sun and rain, when lying long upon the deck of a ship, or hauled up upon a shore. Nor will such boats burn. If a ship takes fire at sea, the boats, if of iron, can never be injured by the conflagration. Nor can they be sunk. For they are provided with air chambers in various parts, each separate from the others, so that if the boat were bruised and jammed by violent concussions, up to her utmost capacity of receiving injury, the shapeless mass would still float upon the sea, and hold up with unconquerable buoyancy as many as could cling to her.[7]

A curious instance occurred during the late war with Mexico which illustrates the almost indestructible character of these metallic boats.

The reader is probably aware that the city of Vera Cruz is situated upon a low and sandy coast, and that the only port which exists there is formed by a small island which lies at a little distance from the shore, and a mole or pier built out from it into the water. The island is almost wholly covered by the celebrated fortress of St. Juan de Ulloa. Ships obtain something like shelter under the lee of this island and mole, riding sometimes at anchor behind the mole, and sometimes moored to iron rings set in the castle walls. At one time while the American forces were in possession of the city, an officer of the army had occasion to use a boat for some purpose of transportation from the island to the shore. He applied to the naval authorities in order to procure one. He was informed that there was no boat on the station that could be spared for such a purpose. In this dilemma the officer accidentally learned that there was an old copper life-boat, lying in the water near the castle landing, dismantled, sunk, and useless. The officer resolved, as a last resort, to examine this wreck, in hopes to find that it might possibly be raised and repaired.

He found that the boat was lying in the water and half filled with rocks, sand, and masses of old iron, which had been thrown into her to sink and destroy her. Among the masses of iron there was a heavy bar which had been used apparently in the attempt to punch holes in the boat by those who had undertaken to sink her. These attempts had been generally fruitless, the blows having only made indentations in the copper, on account of the yielding nature of the metal. In one place, however, in the bottom of the boat, the work had been done effectually; for five large holes were discovered there, at a place where the bottom of the boat rested upon the rocks so as to furnish such points of resistance below as prevented the copper from yielding to the blows.

The officer set his men at work to attempt to repair this damage. They first took out the sand and stones and iron with which the boat was encumbered, and then raising her, they dragged her up out of the water to the landing. Here the men lifted her up upon her side, and began to beat back the indentations which had been made in the metal, by holding a heavy sledge hammer on the inside, to serve as an anvil, and then striking with a hand-hammer upon the protuberances on the outside. In the same manner they beat back the burrs or protrusions formed where the holes had been punched through the bottom of the boat, and they found, much to their satisfaction, that when the metal was thus brought back into its place the holes were closed again, and the boat became whole and tight as before.

When this work was done the men put the boat back again in her proper position, replaced and fastened the seats, and then launched her into the water. They found her stanch and tight, and seemingly as good as new. The whole work of repairing her did not occupy more than one hour—much less time, the officer thought, than had been spent in the attempt to destroy her.