It is the opinion of the elegant and acute writer, Mr. Stuart, whom we have so often quoted, that " there is probably no one, whose name is associated with the history of this mechanism, and whose labours have received so large a share of applause, appears to have less claim to notice u an inventor than Robert Fulton." Although we cannot dissent from the strict literal meaning of this observation, we think it would be illiberal not to concede, that it has been chiefly owing to the talent, energy, and perseverance of Fulton, that the crude and previously abortive schemes of other inventors were carried into practical and beneficial operation. Several years elapsed before steam-boats were established in this country. In 1812, a boat, called the Comet, was tried on the Clyde. Shortly afterwards, Mr. Lawrence, of Bristol, constructed a steam-boat, which he tried on the Avon, and finding it successful, proceeded with her through the canals, to the Thames ' • but, in consequence of some of the bye-laws of the Waterman's Company, he was prevented !Vail using her profitably, and under the necessity of returning her to the Avon. After this, steamboats were tried on various rivers, both in England and Scotland, with different success. These were generally, as may be naturally concluded, of a very imperfect construction. The speculation being then extremely hazardous, old boats, and, in some cases, old engines were adopted, to save expense : the consequence of which was, that these experimenters just proved the advantages of steam-navigation, so far as to warrant other parties to construct superior vessels and engines, and thereby reap the profit.
- The construction of the engines in these boats resembled each other pretty nearly, being generally beam-engines, the beam working above the deck, and having an erection for the purpose of covering the machinery, which was gene rally above the level of the deck, the main difference being in the mode of applying the force of the engine to the propelling mechanism in the water. Several of theseplans it will be proper to notice, in addition to those mentioned in the foregoing historical notice.
One method was by a species of folding-oar, which openedoutward when it was moved toward the stern, but which folded into a r space by the reverse motion. Several forma of screws have likewise been suggested and patented ; the screw being immersed in the water, and made to rotate, causing the conti nuous inclined plane of its worm to be forced against the fluid, and, by the reaction of the latter, to push the vessel forward. Apparatus resembling the action of ducks' feet, the fins of fishes, the motion of dogs feet, the opening and abutting of doors, or of flaps upon hinges, expanding and contracting umbrellas. None of these, however, have as yet been found so efficacious as the common float-wheel, on account of the simple mode by which it may be attached to the machinery, as well as from its combining great strength and compactness. A variety of modifications of the eommon Wheel have, however, been tried, to avoid the loss of power and inconvenience arising from the backwater, or water thrown up by the emerging of the float; a variety of which are given in the appendix to " Galloway's History of the Steam-Engine ;" but these form but a small part of the numerous contrivances, designed with the same object, and which have been made the subjects of patents.
Various attempts have likewise been made to give motion to the boat by means of paddles attached to chains, which pass over two drams placed on the side of n vessel, as represented in the drawing, by which it was expected that the effect would be considerably increased by the number of paddles which were acting upon the water at the same time.
It was, however, found on trial, that the great friction of the chains, together with the number of parts, which were exposed to injury, prevented their cessful adoption. Another method, upon a somewhat similar principle, is sented in the accompanying figure. The cranks a a are moved by the engine, and turn with them the horizontal bar, to which are fixed the vertical paddles. By this method all the paddles are immersed in the water in a vertical position, and raised out of it in the like manner; but although the back-water is avoided by this method, yet it is obvious that another difficulty is encountered, of a more formidable nature ; which is, that the motion of the paddles, in entering, is ex ceedingly slow, and probably slower than the speed at which the vessel passes through the water ; so that, unless the speed be too great when the paddles move at their greatest velocity, namely, when the cranks are vertical, they must, at entering and leaving the water, considerably impede the motion of the boat.
A method of keeping the paddles vertical, during the revolution, is described by Mr. Robertson Buchanan, in his " Treatise on propelling Vessels by Steam," which he thus explains: " If two equal rings or circular lines in the same plane, or in planes parallel to each other, be conceived to revolve each urn its respective centre in its own plane, with one and the same uniform velocity, and in the same direction with regard to parts of the rings, or lines alike situated, and any point be taken in one of the lines or rings, and a right line to be drawn from that point, parallel j to a line supposed to join the centres, until it meets the other ring or circle, then the right line so drawn will be equal to the line of distance between the centres, and will continue equal and parallel to that line of distance during the whole of every revolution so made." The dotted circle and the black circle in the accompanying figure, denote the rings or circles mentioned in the theorem, and y and x denote their centres; the lines 1 a, parallel to, and equal to the line of distance of the centres will continue equal and praUel to that line of distance, in the position of 2 c, and 3 e, and 4 g, and all other positions into which the point I can be brought, during the uniform, equal, and similarly directed revolutions of the two circles.