produce an up and down motion; on the other side is an eccentric doing precisely the same thing; and the object of this is to show that the substitution of a crank for an eccentric, or an eccentric for a crank, will not make any difference; so you will find in some other details that the substitution of an equivalent is, in point of mechanics, precisely the same thing. You are not merely to look to the shape, but to the substance: you are first to seize the spirit of the invention, to see wherein the ingenuity consists,-to see what was the device by which the man who claims the invention overcame the difficulty to be struggled with. In the present case I say it was this, it was by having the principal wheel connected with an eccentric wheel, and then made to play into each other by a series of movements, one arm of the eccentric being stiff and fixed, and the others moveable, for the purpose of obtaining the proper angle to float-boards; wherever you find such an arrangement it will be the plaintiffs' invention. I will conclude, and I am confident you will do justice between the parties.

William Carpmael, Civil Engineer, sworn.-Examined by Sir W. Follett.-I am familiar with the improvements made from time to time for the last fifteen years connected with paddle-wheels; have examined almost everything, if not everything, brought out in respect to paddle-wheels; have read this specification attentively.

Mr. Baron Alderson.-What is the point of invention in this patent?

Mr. Carpmael.-I consider the improvement stated in the specification to be the obtaining any required angle to the float-boards of paddle-wheels, by means of the rods, g, h, i, j, and k, the one of them being a fixed and governing rod, that is, g, the others being moveable. The one fixed rod governs the whole, and the other rods which are connected to the float-boards each by a pin or moveable joint, and the other ends of the rods are connected to a disc.

Examined by Sir W. Follett.-Any angle may be obtained by the construction I have pointed out, and consequent upon the construction: this I believe to be perfectly new. It is an advantageous improvement that paddles should be made to enter in that way. There is no loss of

power; the moment the float-boards get into the water they come fully into action, so much as is immersed, and there is the same advantage in leaving the water. I have seen the defendants' paddles on the vessel called the Levant: they are constructed on the same principle as the one I have described. The float-boards in the defendants' wheel are controlled to move in succession by means of the same rods, h, i, j, and so on, as in the plaintiffs': they are identical; they are each attached to a stem, one to each of the float-boards, by moveable pin-joints, that is, to the stem, f, as it is called in the specification.

By Mr. Baron Alderson.-On each of the float-boards, and to the strap or disc, A, by a further moveable pinjoint; it is a strap revolving upon an eccentric axis, but it is called A, in the specification. In the plaintiffs' model, and also in the specification, the rod, g, is a fixture to that disc, A, which revolves on the axis, B. The axis, B, in the defendants' wheel is a pulley affixed to the side of the vessel, eccentric to the main shaft. In the plaintiffs' arrangement the fixed rod, g, in addition to controlling the other rods, h, i, j, k, also itself operates upon one of the float-boards: in the defendants' the fixed rod, g, is not made to perform upon a float-board directly, but by the intervention of what is called a link, that is, a rod having a hole at each end. There is therefore a deviation from the plaintiffs' arrangement of the eccentric axis being placed or bolted at the ship's side, and the governing-rod, g, not controlling the float-boards directly, but by the intervention of the link I have described. Those are the deviations, then; the main shaft of the steam-engine is thereby enabled to pass from side to side.

Mr. Baron Alderson.-That has nothing to do with it; it is no part of the invention claimed.

The Attorney-General.-Your Lordship will find it extremely material.

Examined by Mr. Baron Alderson.-In the plaintiffs' wheel, in consequence of having the patented combination of the rods, g, h, i, j, k, between the two framings of the wheel, the shaft from the engine is only made fast to one main-plate, the instrument by which the float-boards are controlled being placed between the two framings, in room of being placed on the side of the vessel. [The

witness here entered into a long explanation of the models of the plaintiffs' and defendants' wheels, showing the similarity of the parts and operations in each.] Anything that will make the disc turn round and change the centre is in effect the fixed arm.

Examined by Sir F. Pollock.-No such principle was ever before applied, to my knowledge, to the producing of varied angles in paddle-wheels. I know Buchanan's wheel; it was introduced about 1813; the effect produced in this paddle is that the floats are always parallel to themselves and to each other: they always attain the same angle in one direction, and always retain the vertical line. This invention is quite different in principle to the plaintiffs' paddle; the effect produced is not the same; the means employed to produce the effect are not the same; neither is the utility the same. I am acquainted with Oldham's invention; it was patented in 1827; it is similar to Buchanan's, but there is superadded certain machinery by which a different result is obtained: the float-boards each take such a position that when the upper one is horizontal, the one in the water is vertical: all the others partake of the angle radiating from the centre of the upper horizontal float-board. The principle and effect are not in any manner similar to the plaintiffs'. The angle at which Oldham's float-boards enter and leave the water depends on the diameter of the wheel; in the plaintiffs' wheel any angle may be obtained, whatever be the diameter of the wheel. I know Poole's patent; it was taken out a few months before the plaintiffs': there is a groove in the side of the vessel, to control the movement of the float, so as to produce the change of angle: it does not in any manner resemble the plaintiffs' paddle.

Mr. Baron Alderson.-There is no similarity between the two; you say your patent is taken out for the mechanical means of accomplishing it, and not for the principle.

Examined by Mr. Baron Alderson.-Angles are given in the drawings.

By Sir F. Pollock.-It is desirable, if you have a very fast engine, or a slower engine, that the angles should be altered; the angle will vary for almost every vessel, depending on a variety of circumstances; many persons would like one angle for the same boat, and some would

like another. What I conceive to be the best, would be a float-board that will enter and quit the water as nearly as possible at a tangent to a cycloidal curve, generated by the centre of the float-board. The cycloid varies according to the speed of the vessel, and the speed of the paddle-wheels. I am acquainted with that part of the specification which relates to the steam-engine, and have no doubt that a workman of competent skill could carry that improvement into effect from the description in the specification, and I consider that the mode of producing a rotatory motion described in the specification, is decidedly new. [The witness here described the engine, a model of which was handed to the jury.] I consider it has a variety of advantages, particularly the smallness of the number of parts, the lessening of weight, and the little space required.

Cross-examined by The Attorney-General.-I have seen a steam-engine prepared according to the drawings and specification; it was used to turn lathes,—it worked exceedingly well; I saw a second engine on the same construction, a larger one, but I did not see it at work. The bent stem described in the paddle-wheel, is no part of the invention; neither are the rods, g, h, i, j, k, that connect the bent stem with the disc, A, any part of the invention.

By Mr. Baron Alderson.—I mean, taken by themselves, my Lord, instrument by instrument.

By The Attorney-General.-The disc is no part of the invention; neither is the crank, the cut shaft, nor the paddle projecting beyond its axis, any part of the invention taken separately. It is the combination of all these parts in the manner described, which is claimed as the invention. It is of great importance to ascertain the angle at which the floats should enter the water, but scarcely any two persons agree what that angle should be.

Examined by Mr. Baron Alderson.-If it was required that the float-board should enter the water at a certain angle, say at 45°, I would set the float-board, which is to be in connexion with the rod, g, at that angle on the water line, and mark the position; then carry on the float-board to a vertical position, which would be at its deepest position in the water; then bring the float-board to leave the water at the angle of 45°, by which I should

have the three positions shown in the drawing, and, by the ordinary rule in geometry, obtain the position of the centre of the crank, or eccentric axis, B; the angles being given, any person acquainted with the setting out of work, would readily produce the wheel desired.

By The Attorney-General.-The angle in the plaintiffs' wheel cannot be varied, without altering all the parts for that purpose, other than by raising or depressing the crank in a slight degree, by which the angle will be varied to some extent without reconstructing the parts. The float-boards may enter and leave the water at the same angle, if it is desired. The angle depends on the rods, and the length of the stem, f, and the crank. In the defendants' wheel you cannot vary the angle without reconstructing the wheel. There is nothing in Mr. Galloway's specification to show what the angle ought to be, nor do I think it could by possibility be given. It will vary according to the draught of water of the vessel, the stroke of the engine, and the figure of the vessel. Never heard of Cave's wheel by name, till this suit commenced in the Court of Chancery; I heard of a wheel belonging to a vessel, that run between Dover and Calais; have seen a model of it; it is the same as Seaward's, without the drag link; the fixed arm, g, actuates a float-board, as well as controls the other float-boards; it contains the invention for which Galloway's patent was taken. A few months previous to the commencement of proceedings in the Court of Chancery, I was consulted by Mr. Morgan, as to whether a vessel coming from Calais to Dover, with an infringement of his patent, could be stopped; he did not state the name of the party infringing.

Sir F. Pollock.-If they will show it was published in England before our patent, I will give it up.

Re-examined by Sir F. Pollock.-Have seen ten or twelve sets of the plaintiffs' wheels, one set precisely according to the specification, with the floats projecting. The plaintiffs had, for a considerable time previous to my seeing the Levant and other paddles made according to Mr. Seaward's plan, constructed their wheels in the same nanner that they do now,-perhaps two or three years before that. Having the axis in the centre of the floatboard is decidedly better than having it at the end; it is a better arrangement, but is not different in principle. The drawings attached to the specification give a useful