NEW PRINTING PRESS IMPROVED HARNESS MACHINE. the beholder, but bids very fair to become extensive in its practical utility to the community; the design of the engine is to transport goods or articles by aid of water, any distance, where there is a sufficient quantity and fall for any given distance. Its leading principles consist of a wheel and axis, with floats or buckets, adapted to a race or trough, whose angle of incidence is adapted to the fall, or other circumstantial conveniences. Upon each end of the axis of this wheel is a cog wallow wheel, which works into a rack or cog plate, which is placed upon the top on each side of the race, and which answers for what may not be improperly termed a railway. The engine being situated at the foot of the race, and the water let in, and operating upon the floats, turns the wheel, and by the wallow cog wheels of the axis of the water wheel being geered with the rack on the race, the wheel ascends; and by a more or less partial supply of water, the water-wheel is made to descend with the velocity required. To the engine may be attached any formation or construction of a carriage, adapted to the nature of the articles intended to be transported. -Philadelphia American Daily Advertiser. NEW PRINTING PRESS. I stated some time ago that I had completed a small steam-press, or a press to work with lever power, and with sufficient rapidity to produce 2000 impressions per hour, but could not discover a satisfactory mode of supplying my ink-rollers, and solicited the co-operation of some of my Yankee brethren. A Mr. W. H. Hale, who comes, I understand, from Boston, and is a silversmith, called upon me, and soon removed the difficulty, by the formation of an ink-trough, which, supplying one roller, communicates the ink rapidly to the other roller, and after a short time my model was complete, and is so simple and efficacious, and works with so much ease, that 2500 impressions may be thrown off in the hour, by the 423 introduction of a heavy fly-wheel. The press is worked by a crank, and with the labour of one hand and two boys to feed the cylinder with paper; thus superseding the necessity of steam, water, or horse power. Noah's American Advocate. IMPROVED HARNESS MACHINE. In the present scarcity of drawboys, it gives us great pleasure to announce, that Claud Wilson and Alexander Lang, weavers, Georgestreet, have made a most important improvement upon the French harness machine, which in many respects will be of the utmost advantage to the trade. The French machine costs 157. for a harness 400 of a tye; whereas one upon the new principle can be procured for 5l., and of 200 of a tye, for 4.; the treadle in the former requires to be pressed down nine inches, in the latter only 4. The web which has been selected for a trial is a common imitation shawl; but the inventors are confident that they will be able to work a shawl, plaid, or trimming, with three covers, with one-half of the cards that are required upon the French plan. The machine has been examined by a number of manufacturers, weavers, and mechanics, who have all expressed themselves highly satisfied. It is open for public inspection, and may be seen by applying at No. 139, George-street.-Paisley Advertiser. 424 MR. SPILSBURY'S PATENT METHOD OF TANNING. is placed, then a second hide is laid above it, and a third frame is put above that. The three frames are arranged so that the metal loops of each shall be opposite those of the others; screw bolts are then put through those loops, and screwed up sufficiently tight to prevent any liquor from passing between the frames and the hides. The whole is then set up edgeways, and there being two short pipes, furnished with cocks, in the upper edge of the middle frame, a pipe, in which there is also a cock, that descends from a cistern holding tan liquor, is fastened to one of these by a union joint; and another cock being placed near the bottom, in the same frame, to let off the liquor when required, completes the whole apparatus. The cock at the top, that communicates with the tan cistern, being opened, and the other near to it being also opened, while that at the bottom is shut, the tan liquor will run down between the hides, driving out the air at the other open cock; which, as soon as any liquor appears in it, being shut, the tan liquor will then distend the hides, and press outwards, with a force proportional to the height which the tan cistern is elevated above the frames. The consequence of which pressure will be, that the tan liquor will ouse through the pores of the hides, appearing at the outside like dew; and by thus bringing fresh portions to act continually on them, will, in the opinion of the patentee, cause them to be tanned much more speedily than happens in the common method, in which the hides lie in the liquor, after it has ceased to operate on them, and are only passed into fresh liquor at intervals by a tedious manual operation. The frames are to be made of wood or copper, and if iron should be used for them, it must be well painted, to prevent its making the hides black. In some cases, two skins or hides may be put at each side of the middle frame; and when the whole are well tanned, the tan cock is to be closed, the liquor is to be run off at the lower cock, and the frames separated from the tan pipe and from each other; and the hides being removed, and having their edges pared off, which were nipped or compressed between the frames, are then to be dried and finished in the usual manner. Nothing further is stated in the specification respecting the time which this process will require, but that it must depend entirely on the nature of the hides or skins. The New Repertory of Inventions has the following remarks on the value of this process : "This method of tanning has attracted much attention; and it is reported that hides of that thickness, to require a year for tanning in the common method, can be finished in this in six weeks; and that some skins can be tanned by it in eight or nine days; it is also said, that a very large sum of money has been offered for the patent right. "The theory of the process appears to promise well for quick performance, but on these occasions it is necessary to attend to facts; and we have been informed by some gentlemen in the trade, that the hides are not tanned evenly by this method, but leave spots less acted on by the liquor than the rest; and that leather made in this way is not so durable as the common sort. "The quantity of the hides that must be pared off when they come out of the frames, must certainly diminish the value of the process, and especially when oblong-square frames (such as are represented in the figures of the specification) are used, which, not being of the natural shape of the hides, must cause more waste; which must be worth consideration, even though the parts to be cut away are the least valuable of the hides. "It must, however, be considered that this method of tanning is still in its infancy, and that it will be probably improved in time, so as to diminish some, and totally remove others, of these objections made to it. Let KL be the base of the stand, to be placed on the top of a pedestal parallel to the horizon, by the side of which the arm, NU, is to act. AB is a trough to contain the telescope; at its end, A, a piece of plank or board, GH, is made fast, and is fixed to the base by two hinges, E and R. Near the top of the trough, the arm, NU, is so fixed, by an extended pin, de, as to play in diverse directions. The arm, NU, is to slide in the tube, W, and to be made fast at any desired part by turning the screw at Y until it presses against the arm, and by this means you will fix it very nearly to any desired altitude. Now one side of the tube, W, being made to project, and a hole, X, made through it for the purpose of screwing it to a sliding piece, Za is then capable of sliding in an inlet groove, OP, supported by hinges at S and T; whence, taking hold of the arm at V, and sliding it toward or from P, Za will have an horizontal movement, by which the telescope and trough, AB, will be elevated or depressed, and with a beautiful slow movement. As for the horizontal range, or for turning the whole to any azimuth, the operation is so simple as to require no explanation. The telescope thus supported, and the pedestal resting on sand, I have found by experience that nothing will disturb it but the wind. NOTE. To all telescopes of great power it is better to have two finders, the one of a great field of view. MATHEMATICAL CASE. SIR,-In page 374 I find the question" Can a straight line touch the circumference of a circle in any point at a less angle than 90°, with the radius drawn from that point to the centre?" I am inclined to doubt the correctness of the conclusion drawn by your plural Correspondents," Discipuli." It apDiscipuli." It appears feasible at the first "dip;" but I think, if the "bucket" be allowed to sink a little deeper, a different conclusion will be drawn. After a careful investigation of those particular propositions of Euclid which bear upon the point in question, I see no reason to doubt the correctness of the conclusions which Euclid has drawn, and which are the reverse of the one drawn by the "Discipuli." As some of your readers may not have Euclid to refer to, I will quote his 16th Proposition, Book III., which bears directly on this point. "The straight line drawn at right angles to the diameter of a circle from the extremity of it falls without the circle; and no straight line can be drawn between that straight line and the circumference, from the extremity of the diameter, so as not to cut the circle. "Let ABC be a circle, the centre of which is D, and the diameter AB; and let AE be drawn from A perpendicular to AB, and AE shall fall without the circle. E "In AE take any point, F; join DF, and let DF meet the circle in C. Because DAF is a right angle, "Again, between the straight line, AE, and the circumference, no straight line can be drawn from the point A which does not cut the circle. Let AG be drawn in the angle DAE; from D draw DH at right angles to AG; and because the angle DHA is a right angle, and the angle DAH less than a right angle, the side DH of the triangle DAH is less than the side DA, (Prop. 19, Book 1.) The point H is therefore within the circle, and therefore the straight line AG cuts the circle. "COR.-Hence it is manifest, that the straight line which is drawn at right angles to the diameter of a circle from the extremity of it touches the circle, and that it touches it only in one point; because, if it did meet the circle in two, it would fall within it. (Prop. 2, Book 11.) Also it is evident that there can be but one straight line which touches the circle in the same point."-Playfair's Geometry. This conclusion appears to me decisive. Suppose the line AG at the smallest imaginable distance from AE, still a line drawn from D, meeting AG at right angles, will form a SECRETS IN SELLING-SIR H. DAVY'S COPPER SHEATHING. right-angled triangle, DAH, of which DA (the hypothenuse) will be the greater side; and, therefore, DH is less than DA, and within the and (by Prop. 2, Book 1.) AE cuts the circumference in two places. circumference Your Correspondent (or dents) will not need to be reminded, that a mathematical point or line is not such as to be seen by the naked eye, nor even by the best microscopes. The points and lines in a diagram are seen, but they are merely a guide to the inward or mental view. In such questions as the above, we must first draw lines at perceptible distances; and if we want to draw conclusions from imperceptible distances, we must carry on the operation mentally, from the facts deduced at perceptible distances. I am, Sir, R. H. [We have also received answers ad Discipulos from Amicus, Acute Angle, Napier, B., J. P.G., F.O.M., and Zero, one or more of which we shall (probably) give in our next.— EDIT.] SECRETS IN SELLING. SIR,--I am afraid C. M. will still find himself a little in the mist, notwithstanding the ingenious solution given by F. O. M., page 381, for how he is to find the value of 0 from the two heights of the barometer? I shall propose the following question to be solved from F. O. M.'s formula: Suppose a cubic foot of cork exactly balances 241 ounces avoirdupois of lead, when the barometer stands at 28o, what will be the weight of the same piece of cork when the barometer stands at 31°, the temperature of the air in both cases being 55o ? I am, Sir, Yours respectfully, 427 SIR H. DAVY'S COPPER SHEATHING, The following paragraph from the Plymouth Journal has, during the past month, gone the round of all the newspapers : "Failure of Sir H. DAVY's Plan for the Protection of Ships' Bottoms. "The plan some time since re, commended by Sir H, Davy, to prevent the oxidation of copper on ships' bottoms, and which was adopted by for the interest of science, has not Government, with a laudable zeal been found to produce the expected benefits. In the instance of one of his Majesty's ships, which was fitted four years ago upon Sir H. Davy's plan, and which is now undergoing repair in this dock-yard, it appears iron has indeed prevented the oxithat the galvanic influence of the dation of the copper, but the bottom of the ship is found, as in the case of wood-sheathing, to be foul with weeds and barnacles, to provide against which, copper bottoms were originally adopted. We understand that orders have been received to discontinue the fitting of his Majesty's ships upon Sir Humphry Davy's principle." We deferred copying this (apparently exaggerated) statement into our publication, until we should see what answer or explanation it would draw forth from the learned President of the Royal Society, or his friends. In the Annals of Philosophy for the present month (Oc tober), Mr. Children has given the explanation for which we waited. It appears from this, that Government have not abandoned Sir H. Davy's plan altogether; that the application of his protectors is merely suspended for sea-going ships; and that it is ordered to be applied to all ships in good condition in ordinary (the Royal Sovereign, for instance), as also to stationary ships, such as sheer-hulks, receiving-ships, &c.Mr. Children adds the following remarks, in the spirit of which we fully concur : 66 "It is not for us to question the propriety of the measures adopted by the Lords Commissioners of the Admiralty, though we cannot help |