pose, may be used. The only thing which I claim as new, is the form given to what is usually denominated the cylinder, by making it smaller at the centre than at the ends, as herein described; the effect of which, it has been experimentally proved, is to prevent that annoyance from the current of wind and ** dust, produced in other machines for thrashing grain. "Although I have spoken of the revolving body as formed by the union of two truncated cones, the effect will be similar if, instead of using the double cone, as described, the cylinder be made concave, in a regular curve, reducing its diameter in the middle, so that it shall be an inch, or upwards, less there than at the two ends.-JOSEPH ROSS." MACHINE FOR CLEANING CLOVER AND OTHER SEEDS, Joseph Ross, Boundbrook. -"I construct a frame to sustain a horizontal cylinder, and other parts of the apparatus, to be presently described. The cylinder may vary in length and diameter, according to the power by which it is to be driven. The cylinder is to be set with teeth of two kinds; one set of teeth may be from one-fourth to half an inch in length. These form circles round the cylinder, the circles being an inch, more or less, apart. Between these, rows of long teeth, wires, or sprigs, are driven, which could not stand out more than one-sixteenth of an inch, their office being to rub the seed from the husk; a similar effect may be produced by covering the cylinder with punched sheet iron, or in other well-known ways. "I use a concave which surrounds the cylinder for about three-quarters of its circumference. The part directly under the cylinder, extending about one-quarter of its circumference, may be of punched sheet-iron, or of wove wire, with meshes of such size as will allow the seed, but not the chaff, to pass through. The remaining part of the concave, extending up to the apex of the cylinders, may be left smooth. The distance between the cylinder and the concave must be sufficient for the passage of the larger teeth. "The seed to be hulled is put into a hopper above the cylinder, the opening through the bottom thereof extending the whole length of the cylinder. In front of the cylinder I employ rubbers, which are made by taking wide strips of sole leather, the length of the cylinder, there being three, four, or more, such strips; these I confine between pieces of thin board, one piece being placed between each strip. The edge of the leather, where it touches the cylinder, projects beyond the thin boards, so as to give it the necessary play; each piece of leather is so notched as to allow the longer teeth to pass. The leather rubber, thus formed, slides in against the cylinder, and is, therefore, capable of be ing adjusted so as to press against it with greater or less force. "When the seed has passed the leather rubbers, the greater part of it falls through an opening on to the floor, whilst the chaff and the remaining seed are, by the action of the longer teeth, carried immediately over the perforated iron, or the meshes of wire-work, of which the lower part of the concave is formed. "At the point where the smooth part of the concave commences, an opening may be made by lowering the bottom part of the concave, which is hinged in front for that purpose. Stones, or other hard substances, may be thus readily removed. A strip of leather is fixed along the edge of this opening, which extends to the cylinder, serving to check the too free passage of the seed round with the chaff, whilst, by its elasticity, it will allow the long teeth to carry the chaff beyond it. The back edge of the hopper has also a similar piece of teether upon it, which extends to the cylinder, and arrests the chaff, causing it to be blown out through an opening immediately behind the hopper, whilst that whieh contains seed will, from its greater weight, be retained, and pass the leather, to be again rubbed. "What I claim as new in the foregoing machine is the combination of long and short teeth in the cylinder, operatinr in the manner, and for the purposes, set forth. I also claim the leather rubber, constructed and acting in the manner described; not intending, by these claims, to limit myself to the precise arrangement set forth, but to vary the same in any way, whilst I produce the same effects by machinery operating substantially upon the same principle.-JOSEPH Ross." IMPROVED PLOUGH, Nathan Robinson, New York." The body of the plough is best made of cast-iron, as such instruments are now usually made, but the improvements which I have made are independent of the material, consisting of such alterations in its form and relative dimensions as are calculated to obviate the objections most commonly made to the ploughs now in use, namely, their running hard, and their liability to become choked with dirt. The principal alterations I have made in the plough, to effect these objects, are by giving greater length to the body of it, and less curvature to the mould-board, than have usually been given. In describing these improvements, I shall set down certain precise measurements and proportions; but it is to be distinctly understood that I do not intend thereby to limit myself in these particulars, but merely to exemplify the principle upon which I proceed, and to give information to those who might otherwise be at some loss in carrying my plan into operation. At "From the point, or nose, of my plough, to the junction of the shank and mouldboard, it is formed to a radius of about 72 inches, keeping the same curvature, or nearly the same, through to the hinder part of the mould-board, this being about the medium convexity which the under side of the furrow slice naturally takes in being raised and turned over. From the commencement of the circle at the point, or nose, I sweep up. till I have raised the share of my plough about 10 inches from the bottom of the land side, this being the seat, or junction, of the stem to the mould-board; presenting a thin, flat wedge, and a nearly straight ascending plane, of about 20 inches to the earth. this point the furrow slice lies on an angle of 31° from the surface of the earth from which it is raised. From the junction of the shank to the mould-board, I run back on a straight line about 28 inches, and on an angle of about 400 with the land side, inaking my plough about 21 inches wide at the hind part. My share I proportion in length to the other parts of my plough; commencing about 2 inches above the point, I draw a line back on about the same angle with the land side that the upper edge of the mould-board has, till I kave obtained a sufficient width from the land side, which is about 12 inches. The long edge, which is thus presented to the furrow slice, separates it readily and evenly from the solid earth. At the termination of my share, which is about 16 inches from the startingplace, at the point, I turn an angle in the lower part of my mould-board, in the usual manner; but I carry the bottom edge of the mould-board back even with the bottom edge of the land side, leaving the heel thereof as many inches from the land side as the share is at the widest point; these three points then stand at right angles with each other. The bottom of my plough being about 30 inches long, I make the hind end of my mouldboard to slope back sufficiently to give to my plough a length of about 47 inches from the point, or nose, to the extreme point of the mould-board. "I will now give some further particulars respecting the relative dimensions of my plough, taken from one which I have made, and the operation of which I have tested by satisfactory experiments. Share on an angle of 310 with the bottom of the land side; the upper edge of the mould-board is at an angle with the land side flat-wise, 40°; the edge of the share with the land side, 32°; length of the plough on the bottom of the shank to the point of the mould-board, 30 inches; the edge of the share, 17 inches; from the termination of the share to the heel of the mouldboard, 13 inches; cutting width at the point of the share, 11 inches; parting off width on the bottom, 11 inches; circle of the shin, 72 inches radius; circle of the concavity of the mould-board, nearly the same; from the nose to the extreme point of the mould-board, 46 inches; width of the mouldboard, 13 inches; overjet, 74 inches. "It will be manifest to any person that these measurements may be departed from, to a certaint extent, without thereby essentially altering the character of my plough; and it will also be evident to those who are acquainted with the construction of ploughs in general, that the form which I have given to mine, by proportioning the different parts to each other, is such as impresses upon it a character by which it will be readily distinguished from others. What I claim, therefore, as my invention, is a plough formed upon the principles, or in the manner, herein set forth, by which it is made to run more easily and cleanly than those now in uses.NATM AN ROBINSON." given place to a description in your last magazine (page 41), are improvements by which a greater power can be given to its action, than by the common application of the handspike. For, however well adapted it may be, when the resistance to be overcome is much less than the power which can be so applied, it is a fact, well known to seafaring men, that there are times when the utmost exertions of the whole ship's company, by such means, are unequal to purchasing the anchor. And it still more frequently happens, that by their long repeated efforts, they are unable to advance the pall cylinder even one tooth in its revolution, that is, to bring in about two inches of the cable, until aided by some lucky wave or changed position of the vessel: consequently, in such cases, much time and strength are expended before a vessel can be got under way, merely for want of additional power. This has led to various mechanical contrivances, most of which have been modifications of the cogwheel and pinion, but which have severally proved defective and unfit for the causualties to which they are exposed on ship-board, particularly from the changes which take place in the distances of the centres, by the straining of the windlass, bits, or timbers, whereon they may be fixed. Complicated machinery, however powerful, is decidedly objectionable. Indeed, any apparatus to be applied to a ship's windlass should be simple in its construction, direct in its action, compact, strong, and not liable to be deranged, and withal, not too expensive. That Young's patent purchase, of which I herewith send you a description, combines these properties, will be readily admitted by those of your readers who are particularly acquainted with the working of a ship's windlass, as it is also by those who have adopted it in its present complete state. Fig. 1, is a back clevation of a ship's windlass and bits, fitted with Sowerby's patent pall and riding-chock in the middle, and Young's patent purchase at each end within the garrick bits. Fig. 2, shows a section of the windlass body, and an end view of the purchase and starboard garrick bits. The patent purchase consists of a strong cast-iron wheel, firmly wedged upon the body, with semi-elliptic cavities in its surface, adapted to hold the sides of the link of a chain which embraces it, and a pinion with similar cavities in its surface. The pinion is keyed upon an iron axle, working in a carriage placed on the deck, aud bolted down to a beam abaft the windlass. Ratchets are also keyed upon each end of the axle, and worked by a palling box, from which a socket arm is continued for receiving the handspike. The two ends of the chain are connected by a shackle made on the segment of a link, so that it also fits the cavities in the wheel and pinion. The chain may be tightened or slackened by means of adjusting wedges, which are fitted on the carriage. The drawings represent the handspikes in their places, which, on being depressed, bring the pinion round, and with it the windlass body, with a power proportioned to the size of the wheel to that of the pinion. The usual proportions adopted are about four to one; consequently, one man using the purchase, is nearly equal to four men applied to the windlass in the usual way. Hence, with it, a small number of hands may get the anchor, when the whole ship's company would be unable to do so without it. In addition to its great power, it possesses other important advantages, a few of which I shall briefly enumerate as follows:-It is not liable to be injured by the heaving or pitching of the vessel in a heavy sea; the endless chain which embraces the two wheels fixed upon the windlass body and axle not being tight, but passing easily and loosely round them, added to the peculiar form of the wheels, renders them incapable of being thereby deranged or broken. The men can with the same handspike, at pleasure, use the common windlass, or take advantage of the patent purchase, their faces being always towards the ship's bow. The handspikes not requiring to be taken out (as they fleet themselves by the ratchets), no time is lost in re-inserting them, as with the common windlass alone. Should the cable ride, or a handspike foul, it allows the windlass to be turned backward. It is a considerable security to the windlass necks, as its pull is in an opposite direction to that of the anchor, and when riding, it answers as an extra riding-chock. It offers no obstruction to the free use of the windlass, having no spindle passing case, where it has been put to the proof, has been the means of saving the vessel; nor has it conduced less to durability than it has to safety. It is clear that the same means would produce the same effect, if adopted in merchant-ships. The plan is also in existence in the merchant steam-ship Royal Victoria, now building in Leith. I cannot look on the conduct of the Society in any other light than that of discouraging the building of strong, safe, and durable merchant-ships. -I am, Sir, &c. (Signed)" JAMES BALLINGALL. "N. W. Symonds, Esq." I received acknowledgment of receipt of this letter. I presume I need hardly add that, finding I was to derive no advantage from additional safe construction of the vessel proposed to be built, I declined ordering her, and I leave to your readers, whether 1 have not proved your correspondent's assertion, "that we never shall have a safe merchant-ship while the worthies at Lloyd's can prevent it," to be correct. I shall trouble you with one more letter on the subject, And am, Mr. Editor, ROYAL CORNWALL POLYTECHNIC SOCIETY. THIRD ANNUAL EXHIBITION. (Abridged from the Falmouth Packet.) On the 29th and 30th of September last, the third exhibition of this Society was held at Falmouth. The attendance was numerous beyond precedent, showing that the Society daily grows in public favour. Mr. Davies Gilbert took the chair amidst loud applause, and briefly addressed the company. He was highly gratified to find that the institution had continued to excite an increasing interest. As a Cornishman, he felt the highest gratification in considering how high his native county stood in the scale of scientific research. It was with peculiar gratification he felt himself able to state, that the institutions of Cornwall stood high in the estimation of scientific men throughout Europe; and that at the late meeting of the British Association in Dublin, the consideration had considerable influence in the fixing on Bristol as the next place of meeting, that the members of the Geological and Polytechnic Societies of Cornwall might have greater facilities for attending. It would be unpardonable in him, were he to omit to notice how much the Society was indebted to the ladies, who had contributed in so considerable a degree, to render the exhibition both interesing and attractive The hon. gentleman next noticed those articles in the exhibition, which he considered to possess peculiar merit; after which he proceeded to deliver the prizes to the successful competitors, to each of whom he addressed a suitable compliment or an encouraging observation. The following is a list of the prizes : MECHANICAL AND SCIENTIFIC INVETONS. Judges-Messrs. G. S. Borlase, J. S. Enys, R. W. Fox, W. J. Henwood, N. Harvey, W. Petherick, and W. Richards. New Air Pump, Mr. T. Jordan, PenzanceFirst silver medal. Detached Lever Striking Watch, Mr. H. Dobbs, Helston-Second silver medal. Plan for Measuring the Length of the Stroke of a Steam-Engine, Mr. Phillips, Halse- Motion for Raising Miners, Mr. M. Loam, Portable Punching Press, Mr. R. Hosking, Plan for Measuring the Stroke of the Engine, Naval Architecture. Judges-Messrs. W. Broad and F. Symons. Model of a Ship, J. S. Enys, Esq.-First bronze medal. Model of a Corvette, Mr. R. Piper, H.M.S. Astræa-Second prize, value 17. (Then follows a list of prizes in the Fine Arts, (the most remarkable among which is one for a model of the Laocoon, in slate, by R. Burnard, of Fowey, a youth of 16 years of age,) and also in Natural History. PREMIUMS. The Premium of Ten Guineas, offered by J. S. Enys, Esq., for the best Plan for Mea. suring the exact number of Feet of the Acting Stroke of a Steam-Engine, was awarded to Mr. M. Loam, of the United Consols Mines. The Premium of Ten Guineas, offered by J. Taylor, Esq., for the best Plan for Measuring the Supply of Water to the Boiler of a Steam-Engine, was awarded to Captain T. Richards, of Wheal Vor Mine. The Premium of Ten Guineas, offered by John Buller, Esq., for the best Essay on the Natural History of the Pilchard, with a view to the Fisheries of the County, was awarded to Mr. J. Couche, of Polperro. For the second best Essay, by Mr. H. Chester, Penzance, the Society awarded the first bronze medal. The gentlemen to whom the two last essays were submitted, to consider whether the writers had fulfilled the conditions prescribed by Mr. Buller, made the following report: "Two Treatises on the Natural History of the Pilchard have been submitted to us, which appear to fulfil the conditions prescribed bg John Buller, Esq. Both possess merit, but we are of the judg ment that the essay by J. C. has the superior claim to the premium of 10%. 108. "In making this award, we exclude from our consideration some controversial comments, contained in this paper, relative to the comparative merits, antiquity, &c., of the two modes of conduct. ing the pilchard fishery with seans and drift-nets. We recommend that the opinions of the author on these disputed points be omitted, if his treatise be published, and that there be introduced in the form of a note or supplement, some interesting exiracts from the other treatise. "We think it desirable that a bronze medal be presented to the author of the last-mentioned essay. "We earnestly recommend that encouragement be afforded by the Society, te the further prosecu tion of inquiry into the history and habits of the pilchard-to the practical trial of various methods of attracting the fish to the shore-to the discovery of some contrivance for catching shoals of pilchards in deep water with facility and safety-and of a simple plan for destroying or preventing the attacks of "skippers," with which these fish are occasionally infested in the cellars-and to the curing of pilchards as red-herrings are cured-and in a cheaper and more expeditious manner for exportation; such, for insfance, as that practised on the coast of Spain. "It will also be a matter of much interest, and perhaps of utilily, to trace the history of the pilchard fishery during the last 200 years or more, with a view to ascertain the various modes of catching pilchards adopted by our ancestors-the number of hogsheads taken annually-the quantity consumed in Cornwall and Devonshire-and the prices obtained at different periods, for the fish sold when fresh or when ready for shipment. Also the number of complete seans and of drift-nets employed, with a statement of their value, and the amount of capital and persons employed afloat and ashore, in the prosecution of this extremely interesting and beneficial pursuit. We trust that the gentleman who has so liberally offered the premium of 107. 10s. on the present occa-ion, will, at a future period, have the atisfaction of finding that he has conduced materially to the weli-being and success of one of the most prominent interests of Cornwall." One of the Lander prizes, offered by Charles Fox, Esq., Perran, was awarded to Mr. G. Wheatley, Falmouth, for a Map of Peru. The prizes having been delivered, Mr. Gilbert announced that the Rev. Canon Rogers had offered a prize of 10l. for the best mode of lighting mines; after which Sir C. Lemon proposed that the thanks of the Meeting should be given to the Chairman for the kindness and ability with which he had discharged the duties of that office. This motion was agreed to unanimously, and Mr. Gilbert returned thanks in a short speech. On Wednesday, Sir C. Lemon in the chair, it was proposed and carried, that a silver Medal of the Society should be presented to the King, as a testimony of the gratitude felt by the Society for his Majesty's condescension in patronising the Institution; and that silver medals should also be presented to Davies Gilbert, Esq., the President, and Mr. Watt, the descendant of the celebrated James Watt, whose resemblance the medal bears. Amongst the articles that attracted attention were the following: An Air-Pump, by Mr. Jordan, on a new construction. Its merits consist in the application of a rotary motion, whereby the certainty of the piston's descending to the bottom of the cylinder is insured; and the mechanical movement of the valve effects a more perfect vacuum than has been hitherto obtained, so far as our knowledge extends. Laocoon-The award of a silver medal for this piece of sculpture, in relief, on slate, elicited unusual approbation. It was copied from an engraving on wood in the Penny Magazine, by a youth of sixteen years of age, named Burnard, a mason, residing at Fowey, without any instruction in the art, and with tools made by himself, or by a blacksmith under his direction. Much curiosity was evinced by the company to see this extraordinary genius; who, under the fostering care of those disposed to assist and reward native talent, may one day shine in the annals of our county. Model of a Machine for Measuring and Indicating the Length and Number of Strokes performed by the Steam-Engine, by Mr. M. Loam. This machine consists of a notched cylinder connected by wheel-work with several dials, intended to register the work performed by the engine; the first dial registering every 10 feet of stroke, the second every 100, and so on in a geometrical series, whose ratio is 10 feet. These dials may be increased or decreased, to suit the views of those who use the machine. We believe there is a trifling error in the dials for the purpose intended, as they indicate the measure of the arc performed instead of its tangent; this, we suppose, can be rectified.-There was another model exhibited, on the same principle, by Mr. Hosking, of Perran Wharf; and a plan by Mr. Phillips, of Halsetown; both of considerable merit, as the prize list indicates. The premium for the best Plan and Model for Raising Miners out of the Mines was not awarded, but the bronze medal was given to Mr. M. Loam, for a model exhibited by him as possessing simplicity and merit. And on |