The object of the patentee is to prevent the leakage to which cocks are liable, by the use of an elastic plug or stopper; fig. 1, is a section of the improved cock; a, the passage for the liquor to pass from the barrel; b, the mouth or nose of the cock; c, an elastic substance or cork rivetted to the screw plug, d; this screw plug when turned by the handle e, presses the cock c over the passage a,

and down upon the bearing just above the mouth b.

Fig. 2, is another view of the mouthpiece. The mouth, or orifice, a, in the plug b, is placed opposite the passage c, through which the liquor passes; the elastic substance or cork d, is fitted in the plug, which, when turned round by the handle, presses on the passage c— thus preventing the possibility of leaking.

On Saturday last this important case was tried in the Court of Exchequer, before Lord Chief Baron Abinger and a special jury. We are happy to see so evident a desire to support patentees in their rights, as that evinced by his lordship in his summing up. It will tend to give greater confidence to capitalists to embark in the prosecution of important discoveries, when they see the legal tribunals leaning rather towards than against them in the support of their property-as, in fact, all judges are enjoined to do, in the terms of the patent.

Mr. Galloway's patent wheel, the subject of the trial, was described in the Mechanics' Magazine, vol. xxiv, p. 241. See also further particulars, vol. xxviii, p.363.

Galloway v. Bleaden.

The case on the part of the plaintiff's was, that Mr. Galloway had invented an improved paddle-wheel for propelling steam-vessels, for which he obtained a patent on the 18th of August, 1835. The invention consisted in a division of the floats into segments, and so arranged in a cycloidal curve as to cause all the five or six segments into which each float was divided to enter the water at the

same time and at such an angle as most diminished the shock occasioned to the vessel by each stroke of the paddle; whilst the segments, when the float reached a vertical position in the water, became joined together as it were, so as to present an undivided surface to the water, and so increase the power of propulsion; and lastly, the float, when passing out of a vertical position, by becoming again divided, offered less resistance to the back water, and, consequently, less retarded the speed of the vessel than if undivided. The action was brought against the defendant, as secretary to the Commercial Steam-packet Company, for an infringement of this patent; to which he pleaded, in addition to the general issue of not guilty, that the invention was not new, as it had already been discovered and used by Mr. Field in 1833; and that the specification wast not sufficiently intelligible to render the invention of general utility to the public. Several models, illustrative of the alleged invention, were produced, and a comparison made between them and models of the wheels of two of the defendant's vessels, the Grand Turk and the Chieftain, to show that the latter were made upon the principle of the plaintiff's specification. Witnesses were also produced to prove that workmen of compe. tent skill could make the patent wheels from the information contained in the specification, and that the improvement in question was not known in the trade previously to the date of the plaintiff's patent.

The defendant's counsel relied mainly on the ground that the invention had been discovered and used long before the date of Mr. Galloway's patent by Mr. Field, of the firm of Maudsley and Field; and that gentleman, being called as a witness, stated that in 1833 he constructed a wheel on the improved principle now in question, which, upon application to the Lords of the Admiralty, he obtained a promise from them that he should have an opportunity of trying upon the first vessel that came to be prepared; that opportunity, however, was never afforded him, but he made an experiment upon a steam-boat, called the Endeavour, plying between London and Richmond, by substituting one of his improved wheels (of which a model was produced in court) for one of the Endeavour's wheels. At the end of six weeks, however, the new wheel was removed and the old wheel replaced; because, according to the statement of the captain, the boiler was not large enough for the machinery to work it properly. In that same year he entered a caveat at the Patent-offices; and in 1835 he made a great number of experiments on the subject at his manufactory; but it was not until the spring of 1836 that he fitted up a vessel called the Doren Castle with

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wheels upon the improved principle, which were similar to the wheel tried upon the Endeavour in 1833.

The defendants, it was urged, had twice acknowledged the plaintiff's patent right, having on one occasion purchased their patent wheels for one of their vessels, and on another, in 1837, paid them 401. for a license for Mr. Field to use their specification in constructing wheels for them - the latter, in 1838, having fitted up the Great Western with wheels on the patent principle.

The Lord Chief Baron summed up the case to the jury, and left three questions for their decision; namely, whether there had been any infringement of the plaintiff's patent by the defendants; whether the invention was new and unused at the date of the plaintiff's patent; and whether the specification was sufficient. With respect to the principal question, as to whether or not the invention was new, the mere fact of a series of experiments having been prosecuted previously to the attainment of the object to which they were directed could not prevent another inventor from availing himself of the experiments, and then adding the final link which was necessary to bring them to a successful issue. If, therefore, the jury thought that up to the month of August, 1835, the date of the plaintiff's patent, all that Mr. Field had done rested in experiments, those experiments afforded no ground for disturbing the plaintiff's patent, and in that case their verdict should be for the plaintiffs.

One of the jury wished to ascertain whether the wheel tried on the Endeavour was on the principle of the cycloidal curve; or, if the model of it were not in evidence, whether it might not be examined and compared with the original by some competent person.

This question gave rise to some discussion between counsel; ultimately

The learned Baron said that, as the person who had made the model was not present, he could not allow it to go before the jury.

The Jury then returned a verdict in favour of the plaintiffs, with nominal damages.

NOTICE OF A DIOPTRIC LIGHT ERECTED AT KIRKCALDY HARBOUR, WITH DESCRIPTION OF THE APPARATUS FOR CUTTING THE ANNULAR LENS TO THE TRUE OPTICAL FIGURE. BY EDWARD SANG, ESQ., F.R.S.E., CIVIL ENGINEER,

EDINBURGH.

[Read before the Society for the Encouragement of the Useful Arts in Scotland.]

The harbour of Kircaldy, like the greater number of harbours on the coast of Scotland, is tidal, being left completely dry even at the ebb of neap tides. The larger class of vessels which frequent the port, can only

enter the harbour at or near the stream; and thus the increased commerce of the place had rendered it an object of some importance to have the entrance thoroughly lighted.

The harbour Commissioners having, in the summer of 1836, resolved to place a light at the east pier, my brother, Mr. John Sang, suggested to them the propriety of surrounding the intended gas-burner with an annular lens, so as to render useful the light that otherwise would have proceeded upwards. Having, however, felt some doubt as to the possibility of constructing a lens of this kind on so small a scale, he consulted me on the matter, and the ultimate result was, that I undertook to supply the lens.

My object in undertaking, at that time, such a task was two-fold. In the first place, I was desirous that no difficulty either in expense or in workmanship, should prevent such a benefit to the harbour; and in the second place, having been engaged in a long series of experiments on the art of cutting, and having arrived at what I conceive to be some general principles, I was willing to regard the formation of the lens as one of those experiments, or rather as a kind of test of the truth of the detected laws. The entire success of the attempt, has exhibited the possibility of turning or planing glass and of polishing it, to almost any required figure, and that with a degree of precision sufficient for many optical purposes.

The annular lens invented by M. Fresnel, and applied by him to the Phares of the French coasts, as also by Mr. Alan Stevenson; to some of our lighthouses, is a solid of revolution generated by turning the section of a common lens round a line passing through the focus, and perpendicular to the axis of the common lens. The focus is thus in the interior of the annular lens, and the rays proceeding from it, instead of being converged to a conjugate focus, are flashed out horizontally. On the large scale, these lenses are built of many zones, but, in the case in hand, only one piece of glass was used; and the nicety was this, to give to the surface of the small lens that variation of curvature, which is attained on the separate zones of the large lenses.

Three classes of difficulties presented themselves, first, the detection of the proper curve; second, the manufacture of the lump of glass; and third, the cutting and polishing it.

The first difficulty belongs to applicate geometry; and the detail of the method of resolving it, would be here somewhat out of place. It may be enough to notice, that the cylindric form having been determined on for the interior surface, on account of the facilities which it promised in the manipula

tion, the outline of the exterior surface necessarily became a curve of high order. The accompanying drawing shews the section of the lens full size; as it resulted from very laborious calculations.

The form of the lens being thus obtained, the next business was to procure the glass, and here obstacles presented themselves much greater than I anticipated. My first idea was to use flint-glass on account of its high refractive power, but after many attempts, of which the most successful result is presented to the Society, I abandoned that idea, and fell back upon crown-glass. The Messrs. Cookson of Newcastle, furnished me with two pieces, which reached me entire, but one, and unfortunately the better, had received a blow on one of its edges, and a tendency to split showed itself soon after commencing operations: it also accompanies the paper. The other was perfectly sound. On account of the lower refractive index of crown-glass, the lens was carried to less height than had it been of flint-glass.

My first business was to bore out the cylinder. For this purpose, I fixed a tin plate on the point of my drilling spindle, and having primed the edge of it with diamond powder, I cut out a series of grooves parallel to the axis the ridges between these were removed by using intermediate stops on the lathe-spindle; and the whole was then smoothed out by a cylinder of lead with fine emery it was then ground and polished in the usual way for hollow cylinders.

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In order to cut the outside to the proper form, the lens thus bored out was chucked on a turned block of lead, which had been cast on an iron mandril; the surface of the lead being previously covered by a fine thread which was nowhere doubled. By this means the axis of the interior surface was made coincident with that of the lathe.

The evolvent of the required curve was then computed, and the edges of two plates of cast-iron carefully formed to it. These are seen attached to the cheeks of the accompanying frame, and are represented in the drawing. Two pieces of watch-spring were then made to bend over them, so that on uncoiling the springs, one point in each would trace over the curve wanted these springs were then attached to the ends of an axis by adjusting pieces, and that axis had its parallelism preserved by means of a jointed frame.

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This apparatus so prepared, was fixed on the bed of the turning-lathe, and the moveable axis rendered perpendicular to the axis of the lathe. On this moveable axis there were placed the cutters and polishers; it received motion by means of a small pulley fixed on it near one end.

from right to left and from left to right, and thus every possible variety in their direction must be the result; so that the whole effect ordinarily produced by crossing the motions in the usual grinding process, may be obtained. One would therefore, be induced to expect great accuracy from this method; and Mr. Sang has certainly succeeded in giving to the Kirkcaldy apparatus, a very fine polish, which is a matter of great importance.

We consider Mr. Sang's labours as important in regard to the manufacture of Light-house apparatus, and as calculated to improve the manufacture of refracting instruments generally; and we would, therefore, beg leave to recommend that his communication be made known to the public. ROBERT STEVENSON.

ALEX. ADIE.
WILLIAM GALBRAITH, Co
Edinburgh, June 20, 1838.

MR. GEORGE RENNIE'S IMPROVEMENT IN PROPELLERS AND PADDLE-WHEELS.

On Friday last Sir John and Mr. George Rennie, accompanied by a few scientific friends went through a series of interesting experiments in the West India Docks, for the purpose of testing the capabilities of a new form of propeller. In this locomotive age, any invention tending to the improvement of our means and facilities of intercommunication, must necessarily claim a lively and general interest.

The present propeller in an important modification of the old paddle, being an ingenious application of a most simple and beautiful principle in nature, and one generally prevailing where the propulsion of the individual is her object, viz., that of the trapezoidal figure. Hence we may perceive that the tails of fish, the feet of aquatic fowls, and the wings of birds, generally partake more or less of this character; for as was justly observed by the talented inventor (Mr. Rennie), nature never attains her ends but by the best and most efficacious means. The mode by which the propelling power is conveyed to the vessel is not dissimilar to the old wheel, the improvement being principally in the arrangement and form of the floats, which are not very unlike the canoe paddles used by many of the South Sea Islanders. By the way it is worthy of note, as a singular and remarkable feature in the genius of savage life generally, that felicitous adaptation to its own uses of the wise economy with which nature invariably operates her purposes.

The more obvious advantages derived from the present invention, consists in a reduction

of more than one half in the breadth of the paddle-wheel and boxes; consequently, the same amount in the superficial area of the floats, with at the same time an increase of effective power, which, differently from the common method, act with their length vertically, thereby giving so much additional compactness to the whole; a vast improvement it must be admitted in the efficiency of vessels subject to the roll and action of a heavy sea. The other and more practical advantages are in the smoothness of the motion, creating little or no agitation in the wake of the vessel, a desideratum in river or other confined navigation; the facility of suiting the immersion to the variable draught of the vessel, above all, the perfect equalization of the power to the effect in every portion of the float. We understand that the plan theoretically has met with the approbation of Professor Barlow, and other scientific men. The experiment was tried upon a beautiful little vessel, and in a succession of trips made during the course of the afternoon, up and down the spacious area of the import dock, it was particularly remarked the ease with which she turned and threaded her way among the numerous craft lying in the basin. The gentlemen present, among whom was Captain Austin, R.N., expressed themselves in the highest terms upon the satisfactory result of the experiment, being from the peculiar simplicity of the construction admirably adapted for war and sea-going steamers. The patentees we believe intend shortly applying the principle upon a more extended scale.-(From a Correspondent.)

ON

THE APPLICATION OF WATER ΤΟ
ANTHRACITE FIRES.

[From the Mining Journal.] All persons who have been much accustomed to the use of anthracite for fuel, seem to entertain an idea that the application of water has a beneficial effect. It is the invariable custom of the old inhabitants of the districts where no other fuel is used, to wet the coal before putting it on the fire. A wet paste of small culm, mixed with clay, makes a more lively and pleasant fire than stone coal alone. This must arise from the clay retaining a portion of the water until decomposed by the ignited carbon of the coal producing the gases. carbonic, oxide, and carburetted hydrogen. It has been suggested, that the application of the vapour of water to anthracite fires in steam-boilers would supply the gaseous or volatile properties of bituminous coal; there is, however, much difficulty in the perfect development of the principle, arising from the