of the plaintiffs',-they have no right to improve upon it (which, however, they do not),-they have no right to improve on it, and then say, we will use so much of your patent in spite of you. Now, if therefore you find that the defendants have adopted the plaintiffs' improvement, if you find them working on an eccentric,-if you find them connecting the eccentric with the principal wheel, by the moveable rods,-if you find one rod is stiff and fixed, so as to produce this result, even if they greatly improve it, they have no right to take so much of our invention as we have already obtained a patent for. What they should do is, they should obtain our permission to use that, and then, if they have any improvement which they think will render it more valuable, they should take a patent, and work that improvement along with ours they have no right to be pirating that part for which we have obtained a patent. Now I pass to the only remaining point which I shall present, before you hear the evidence, viz., the objection to the steamengine. Such an objection does not come, I think, very favourably. They say, your patent is not good for your improvement in the paddle-wheels, because you have claimed an improvement in steam-engines, which improvement we say is not worth a farthing, and therefore we will destroy the whole. There is no foundation for that objection the witnesses will tell you that it is perfectly novel, and a very considerable improvement, and that there are occasions where a steam-engine so constructed would be used with infinite advantage where no other steam-engine could be used at all. Gentlemen, you are all probably aware, that in a steam-engine, the great point to be obtained is to turn an alternating motion into a rotatory motion; and the object of this invention is, consequently, to turn the motion of a steam-engine into a rotatory motion, and it is done by having the pistons moving not in a straight cylinder up and down, but by having the cylinder semicircular, the piston vibrating backward and forwards in it, and it turns the vibrating motion into a rotatory motion.

:

Mr. Baron Alderson.-What is the objection to that invention?

Sir F. Pollock.-I really hardly know; they say it is of no use, or that it will not work, or something of that sort.

The Attorney-General.-I shall show that it cannot be made by the specification; and, secondly, that it is of no use if it could.

Mr. Baron Alderson.-One of those two objections is certainly open to you.

Sir F. Pollock.-(After describing the operation of the engine, and illustrating it by various models, proceeded.) — That the engine can be made from the specification you will readily perceive. They say, when it is made it will not work. I think that the simple contrivance I have laid down before you proves that it will work; and if it will work, there is no doubt there are situations where it will be of particular advantage. I will point out one. At present the mode in which it is necessary to arrange the steam-engine and the wheels, requires much more room than would be necessary with this engine, and it would be very much lighter, which, in the present increase of steam navigation, is of the utmost importance, and this will accomplish several of these objects. Now, gentlemen, understand me; we do not say they have infringed this,we say, they have infringed the paddle-wheel; but then they come and say, we will try and trip up this patent, if we can, by attempting to prove certain facts which have nothing to do with the inquiry. I am sorry I have detained you so long, but it is necessary that I should put you in possession of the invention; and I believe that simply exhibiting these models before you, has attained the object of putting you in possession of what is my case for the plaintiffs more than if I had, in the absence of them, attempted a laborious and minute description. I have to make but another remark,—it is this; probably the remark may be superfluous to some, and perhaps to all of you; but it is this, that there are in mechanics certain equivalents which are perfectly well known; that which may be done, for instance, by a pulley, may often be done by a crank, and vice versâ : that which may be done by a screw, may frequently be done by a rack and pinion, and are what may be called mechanical equivalents, so that you may, in every machine that can possibly be invented, substitute some other known mechanical equivalent, that shall, to an unwary eye, appear to be a difference, but to the mechanical mind the matter is precisely the same. For instance, on this side of the model is a crank, which is made to

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 princíple 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