Clyde Canal, looked upon Taylor as the party by whom steam-navigation was introduced, the following letters will prove :

Letter from Mr. P. Miller to Mr. W. Symington.

Edinburgh, Feb. 3, 1824.

"Sir,-As I was not at home when you were employed by my father to erect a small steam-engine for him in a pleasure-boat of his, at Dalswinton, with which the first steam experiment now on record was made in the year 1788; nor had I an opportunity of being present at the second experiment, made the subsequent year on the Forth and Clyde Canal, likewise under your management, may I request you to be so obliging as to inform me if you were acquainted with any practical system of steam-navigation that existed prior to that period, from which you could have derived any assistance in carrying my father's project into effect, or if you considered the speculations you were then engaged in as original in themselves at the time; for I never heard of any of the individuals who were engaged in the matter, that had either ever seen or ever heard of Mr. Jonathan Hull's pamphlet.

"Being credibly informed that a Mr. Henry Bell, of Helensburgh, near Glasgow, has publicly stated that my father's experiments failed, might I also request you to be so obliging as to mention what could have given him a handle for a groundless and unfounded mistake; for at least such did not happen at Dalswinton, as I can show by abundance of living testimony at this very day. I also know that there are many still alive who witnessed the experiment both days after the wheels were repaired, who are ready to bear evidence that every thing the reverse of failure took place on that occasion, and that these two days' experiments were as complete in success as any that have hitherto been made; and I would, at the same time, thank you to say if know whether this Mr. Bell was ever amongst the spectators upon the occasion.

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“I have learnt, however, that some years thereafter he applied to you to see the vessel you constructed for the Canal Company, and that you showed and explained every thing particularly to him, from whence he derived the skill he possesses in this matter; and likewise understand that Mr. Fulton, the American engineer, was also at Carron, and had the benefit of seeing the vessel and receiving instructions from you on the steam system which he so promptly and successfully carried into effect.

"I hope it will be convenient for you, on receipt of this, to give me the information of which I at present request the favour; and be so good as to address to me at the Albyn Club, Princes Street, where I shall be for a few days, previous to my return to Dalswinton.

"To Mr. W. Symington."

"I am, sir, your most obedient servant,
(Signed)
"PATRICK MILLER.

From the Right Honourable Thomas Lord Dundas, to Mr. Symington, civil engineer.

"Dear Sir, I was extremely sorry to hear that you had been at the house while I was from home. I beg to explain the cause of my absence, and the step I had taken to meet the chance of your arrival; and I must

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first state, that not having heard from you, I hardly thought you were able to accept the appointment I had made. Having accepted an invitation to sleep at Dunmore on Friday, I came over here during that day, and requested my son's tutor to receive you in the event of your coming to breakfast. Mr. Simpson, however, was not aware that you had been to Carsehall, or he would have done all in his power to make up for my absence, and, if possible, would have induced you to remain till my return.

"It was well known to me that you were the first person who propelled boats by steam, and I well recollect the trial boat lying near the drawbridge. The present model is a different one from that possessed by you; but I do not know if Mr. Bell used at first the 'eccentric' now in common

use.

"The 'auletic wheel' I do not understand; but I will have the pleasure of calling upon you on Wednesday, when I shall be happy to receive your lecture, how much or how little of it may be within my sphere of comprehension.

"I am, dear sir, your very obedient servant,
(Signed)

"THOMAS DUNDAS."

Documents have recently been discovered which substantiate still more fully the claims of Symington. These documents are in the handwriting of John Taylor, the brother of James, the claimant whose rights to the honour we have been examining, and whose name is not so much as once mentioned relative to the matter. We have been thus particular in giving the evidence on this important point. A pension of 50l. has, we believe, been granted to the widow of Taylor for his supposed services as introducer of steam-navigation; nothing was given to Symington during his life, and nothing yet to the relatives he has left behind him. We trust that little time will elapse ere the nation has, through the voice of its legislature, showed a nation's gratitude to the memory of the real introducer of steam-navigation-William Symington.

To afford a ready means of judging of the respective claims of the parties interested, the following summary is appended :

In 1786, Mr. Symington exhibited a working model of a steam-carriage in Edinburgh, and suggested steam-navigation.

In 1788, he superintended the construction of a steam-engine of his own invention, and the fitting of it into one of Mr. Miller's pleasure-boats; which boat was successfully propelled that year on Dalswinton Lake by the power of steam.

In 1789, a larger boat, with a more powerful engine of the same kind, was successfully propelled by steam on the Forth and Clyde Canal.

In 1800, he was engaged by Lord Dundas to construct steam-tugs for the Forth and Clyde Canal.

In 1801, the Charlotte Dundas, steam-tug, was repeatedly tried on the canal, towed vessels there and up the rivers Forth and Carron, into Grangemouth, and carried Mr. Fulton, the American engineer, eight miles on the canal in an hour and twenty minutes. In the same year he patented his direct-acting steam-engine for propelling vessels.

In 1802 and 1803, the second Charlotte Dundas, a larger and more powerful boat, towed vessels on the canal; and on one particular occasion

dragged two laden sloops of seventy tons burden each, the Active and Euphemia, a distance of 19 miles in six hours, against a strong adverse gale.

His experiments were here ended, through the fear of the managers of the canal that its banks might be injured by the undulation caused by the wheels.

In 1811, Mr. Bell's first boat, the Comet, was tried, and set to work on the Clyde. Mr. Bell, as well as Mr. Fulton, had been on board of Mr. Symington's boats, and satisfied himself of their efficiency.

Having thus taken a rapid glance at the main points of interest in connection with the history of steam-boat navigation, we proceed to illustrate the various kinds of modern marine engines. These are of two kindsengines as applicable to the driving of paddle-wheel steamers, and those applicable to "screw" steamers.

The engines adapted for paddle-wheel steamers are of two kinds, " sidelever" and "direct-action." The arrangements of the ordinary side-lever engine will be understood from an inspection of the drawing in fig. 162. As will be observed, this is a modification of the land beam-engine; but as the space overhead in all steam-boats is necessarily limited, the beams are arranged at the lower part of the engine. The cylinder is at a a, bb the working beam, c the steam-pipe, d d the side-rod connecting the end of the beam with the cross-head of the piston-rod e, f the parallel motion ; g the connecting-rod connecting end of beam with crank h, I paddle-shaft, m eccentric-rod, n o p starting handle and valve gearing; rr condenser airpump, worked by the side-lever connected with beam and cross-head of air-pump piston-rod, s s air-vessel, tt framing.

The drawing in fig. 38 shows the arrangement Mr. M'Naught adopts in his double-cylinder marine engines.

In fig. 163 we give a diagram illustrative of the connection of cylinder, condenser, and air-pump. a is the cylinder, b the piston-rod, c the lower, d the upper steam port, e the passage leading to the condenser f. A division is placed between the condenser and the eduction passage e, to prevent the injection-water passing to the lower part c of the cylinder. g the air-pump, hi the air-vessel. We now give descriptions of a few of the details of the engine worth notice. In the air-pump a valve is provided at the bottom plate opening upwards; this is to allow the water to pass from the condenser to the air-pump, but to prevent its return. Another valve is placed at the entrance to the hot-well h (fig. 163); this retaining the

water in the cone, frees the air-pump bucket from an unnecessary weight The air-cone is now frequently dispensed with.

of water.

Two orifices

are made in the hot-well h, fig. 163, one larger than the other; the small one communicates with the force-pump for supplying the boiler, the other with the sea, and is termed the waste-pipe.

Escape-valves are provided to the steam cylinder; the office of these is to allow a passage to the water which collects above and below the piston. The escape-valve at the bottom of cylinder is weighted with a pressure above that of the steam in the boiler; if this precaution were not taken, the steam a would blow through them on being admitted to the cylinder. The upper escape valve is generally placed in the cylinder cover, and is retained by a spring in some instances. In some engines the escape-valves are applied to the ports of the cylinder and kept closed with springs.

The diagram in fig. 164 illustrates the method adopted in side-lever engines in working the slide-valves; fis the end of the cross-head of the

valve-rod, ee side-lever, connected with the end d of the rocking-shaft a oscillating on the centre b, and which is moved alternately up and down by the eccentric lever c, to which the eccentric-rod is attached. g is the back balance-weight; the office of this weight is to balance the slide-valve in such a position that both of the steam-ports are closed when the engine is at rest. In starting the engine the rocking-shaft is moved by hand through the agency of a lever attached to it. In place of a lever, many engines have wheels placed vertically, like the steering wheels of ships. The best starting gear is that known as Stephenson's link motion, used in locomotives, and which, in Chapter V., we have illustrated and described. This also forms the best reversing gear, as by it the full speed a-head can be instantly changed for full speed a-stern without stopping the engines. In engines where this contrivance is not used, the eccentric has to be thrown out of gear before the engine can be reversed. On the crank-shaft, on which the eccentric is placed, a snug or projection is made, as at b, fig. 165; two snugs are also fitted, as at c d. Suppose the shaft revolves so as to bring the face ƒ of the snug b against the snug c, the eccentric moves in the direction of the arrow; but if it is desired to change the motion, the shaft a revolves in the contrary direction, and the face e of the snug b comes in contact with the snug d.

The comparatively large space occupied by side-lever engines, has directed the attention of many of our engineers to devise arrangements by