for consuming the smoke, which have been proposed by numerous recent projectors, on the principle of the air which is to supply part of the combustion, being made to traverse the surface of the ignited fuel before it could come into contact with the boiler, or ascend the chimney. The whole arrangement of this fire-place is very good. A similar mode of supplying the fuel by a kind of hopper, and also the two side openings by which air was admitted, but on a small scale, was practised by the alchemists: the furnace in their hands was called the Athanor. Glauber used a similar one, and describes it in his writings. Mr. Watt also proposed using two fires, one placed beyond the other; on the first grate was laid coals, and the smoke from this fire was made to pass over the surface of the fire made on the other grate with charcoal or coke; so that whatever combustible gas escaped from the fuel on the first grate was ignited by the burning cokes placed on the second.

The first practical application, on a large scale, of the Steam Engine to propelling vessels, was made about this time by a French nobleman.* It It ap

* In the History of Steam Navigation we ought not to omit the name of a M. J. A. Genevois, a clergyman in the Canton of Berne, who, in 1759, published at Geneva a book containing what he called a discovery of the "Great Principle." This was to concentrate power, by whatever means produced, into a series of springs, which might be applied to a variety of uses at the most convenient time, or in the most convenient manner afterwards. He suggested the application of his "great principle" to the mode of propelling a vessel by oars worked with springs. He also proposed the use of an Atmospheric

pears that a Marquis de Joufroy (Geoffroi ?) in 1781 made some experiments on a great scale, on the river Saone at Lyons, with a boat stated* to have been 140 feet long. We are ignorant of the details and arrangement of the mechanism of this vessel, and equally so of the circumstances

Steam Engine, to bend the springs which were to move the oars, and also to work a "winged cart" when the wind failed, and a "winged machine" in any wind-even a quite contrary one. His favourite project, however, appears to have been to use the expansive force of gunpowder, to bend the springs of his oars. He came to England in 1760, to submit his book and plans to the Lords of the Admiralty, who desired him to extract and submit to them that part of his book relating to navigation.-This memoir he printed, with a plate containing figures of the mode of forming and using the oars and the "gunpowder cylinder." -We quote the following anecdote from his pamphlet. "It is true, an honourable gentleman, one of the members of the Navy Office, told me when I appeared before them on the 4th August 1760, that about thirty years ago, a Scotchman proposed to make a ship sail with gunpowder, but having found by the experiments made for that purpose, that thirty barrels of gunpowder had scarce forwarded the ship the space of ten miles, this invention had been rejected. To this I answered, that he acquainted me with a thing quite new to me; that his scheme was deservedly rejected, but that my work was of another kind. I have been since told that it was from the power of retrogradation of one or more cannons on the poop, this man had conceived the hope of forwarding the ship. This put me in mind of a trial a celebrated gentleman made many years ago on the Rhine, by the effusion of the water from a tub on the stern by a hole towards the prow. This was only a sport :-as for the Scotchman's work, it has nothing to do with mine but the thought of gunpowder." p. 20.

"Journal des Debats."-Partington, Historical Account of the Steam Engine.

which occasioned the scheme to be abandoned. The same idea, it would seem, a little after this period occurred to a Mr. Miller, of Dalswinton near Edinburgh, an amateur mechanic, of very considerable scientific acquirements, and of great ingenuity, who published a description of what he called a triple boat, and presented copies of his pamphlet to the different Sovereigns of Europe. The vessel which he proposed to propel by a Steam Engine was a double boat, having one wheel* in the iniddle. It was repeatedly tried on the Forth and Clyde canal, and the experiment, it would appear, was successful. † The date of the trial is not given, but it was probably made after the publication of Mr. Miller's book in 1787, as he there speaks of the scheme as likely to answer. That this gentleman was the inventor of the Steam Boat in the strict sense of the word, "I will not," says Dr. Brewster," venture to affirm; but I have no hesitation in stating it as my decided opinion, that he is more entitled to this distinction than any other individual who has yet been named!"

M. Bettancourt, whose name is well known among

*Brewster.

+ Dr. Brewster, in his supplementary volume to Ferguson's Mechanics, describes the boat as double and having wheels in the centre. We have not been able to see the book. Mr. Buchanan, in his treatise on Steam Boats, says the experiment did not succeed to Mr. Miller's satisfaction.

"I have also reason to believe that the power of the Steam Engine may be applied to work the wheels, so as to give them a quicker motion, and consequently to increase that of the ship." -Mr. Miller, as quoted by Dr. Brewster.

mechanics as the author of some experiments and formulæ on the elastic force of steam, was employed in 1787 and 1788 by the Court of Spain to obtain information and collect models of machines, which it might be expedient to introduce into the Spanish-American mines. When in England, he took occasion to visit the Albion Mills, in which Mr. Watt had erected one of his double impulse engines. Here M. Bettancourt observed that instead of chains, the parallel motion was introduced, from which he inferred that the piston was impelled by the steam, both upwards and downwards; but the interior mechanism he had no means of inspecting. At his return to Paris, he constructed a model having the external appearance of Mr. Watt's Engine; but the steam valves, and the mode of connecting the cylinder and the boiler, re his own invention: these are very imperfect. An engine which is fully described by Prony, was erected y M. Perrier near Paris, from Bettancourt's model: neither its merit, nor date, entitles it however to any notice in the history of the Steam Engine, but for the claim which Prony makes for Bettancourt, as being a second-hand inventor of the mechanism of the double Engine.

Mr. Cooke presented a description of a rotative Engine to the Royal Irish Academy in 1787, which is shewn in the Thirty-first Figure. On the circumference of a wheel eight vanes or flaps are attached by joints, which are formed to open somewhat more than half of their circumference. During the revolution of the wheel, the valves which are on