which bears upon the magnets be 3 cwt., and the magnets to have a sustaining power of 2 cwt., action and re-action being equal, I ask what would be the impinging power exerted by the borer upon the opposing rock, when in operation?-for certainly this is a projectile, and must be calculated accordingly. Suppose the battery to reverse its polarity 10 times a second, and the magnets to separate only the thousandth part of an inch at each pulsation (the clearing of the hole by the recently invented method of pumping water down being approved of), the progress will be found to be three feet per hour. The I do not calculate on receiving any benefit whatever from the attractive principle of the magnets; but I receive in full the whole amount of their repulsive energy. weight which loads the magnets being superior to the sustaining power, the stroke can never have an ascending tendency; the boring machinery must sink while the battery on the surface is in operation, and the weight which loads the magnets follows the descending borer by its own gravity. In boring from the surface, the battery remains above, and the wires connect with the magnet, however deep the workings may be, the points being shielded from danger of soiling by a simple sheath. As the borer will remain constantly at the bottom of the hole, there will be no power lost, as in the other methods, by the displacement of the loose matter at every stroke of the cutter. Not being a practical miner, although I have investigated the theory somewhat, I would leave the form of the cutting tool to those better versed with that subject, remarking that, in cutting hard rock, a single chisel would get wedged in; but by using two common magnets, with a chisel to each -a positive end of the one magnet, and a negative of the other, being presented to each end of the one electro-magnet,--they would work alternately, and at every reversal of polarity; producing a double effect, and freeing each other's chisel at every stroke. This electro-magnetic method of boring admits of being carried to any depth, as the magnets descending with the chisels carry with them the same amount of energy as when at the surface, and as the sustaining power of the electro-magnet may be increased many fold above the example I have instanced, it leaves no doubt in my mind but that a powerful agent is here presented to the mining interest of the country. Regarding lateral borings, it is only necessary to use pressure on the magnets, instead of the heavy weight with which I have illus. trated my description, and the mode in which it will be applied will depend on the nature of the work to be executed. From the friable nature of coal, I should say that this machine might be introduced into the mining of that mineral with certain success, as an auxiliary to the men, in the manner of a pioneer, in cutting always in advance of the workers, leaving them merely the work of pulling down the walls which it has bored into and undermined. I have been as concise as possible, but I hope sufficiently clear to convey an idea of the principle. I have never attempted it in operation, but recommend and leave it to any party who may feel interested. Í believe the idea to be new and good, and take this method to throw it to the world, for others to improve.-Franklin Journal. ON THE COMPARATIVE VELOCITY OF LIGHT AND HEAVY BODIES FLOATING DOWN RIVERS. Sir,-With regard to the phenomenon of light and heavy bodies floating in running water, adverted to in page 580, Mech. Mag., vol. 1. (from an unpublished letter of the late Sir Samuel Bentham), may I take the liberty of pointing the attention of your scientific correspondents to this interesting subject. I confess I entertain considerable doubt, whether the explanation popularly given in the extract, is at all sufficient to account for the phenomenon, or whether, upon investigation, any analogy will be found to exist between the circumstances of a body floating in running water and descending an inclined plane. Of the fact stated, namely, that of the heavy body having acquired a greater velocity than the light one, each being subject to the free influence of the stream, there cannot be a doubt after the palpable instance recorded; but it is highly probable that the cause of this strange effect rests upon other grounds than those assigned, and that the relative velocities are governed by laws in no way connected with the motion of bodies down inclined planes. July 10, 1849. I am, Sir, yours, &c., S. nished with a valve or lock opened or shut by the handle, F. The piston being supposed to be at the bottom of the tube and the valve, F, closed, (the gun, of course, being now run out) it will be seen that when the gun recoils, it carries the piston with it, and a vacuum is thereby produced at the outer or valve-end of the tube, which creates an amount of atmospheric pressure on the inner side of the piston, regulated by the diameter thereof, equal to the force of recoil, and which pressure will of course drive the gun out again. In the case of guns loading at the breach, no further application is necessary; but where guns are loaded at the muzzle, in the ordinary manner, it is necessary to detain the gun from running out until the operation of loading be completed. This is effected by a lever, EE, attached to the inner part of the carriage, and which is furnished with a gab or notch, which falls over the stopbolt or paul at K, and thus secures the gun until loaded; when on lifting the end of the lever at E', the carriage is released and driven out by atmospheric pressure as before described. Should the gun be to leeward, and it be desirable to reduce the force for running out, and the resistance to the gun coming in, by allowing a small quantity of air to enter the tube, the purity of the vacuum will be partially destroyed, and the column of air admitted will form a resistance to the piston when it arrives at the bottom of the tube. The screw collar at D is for the purpose of connection, and also for easing the gun in in extreme training. On the carriage being disconnected at D, or by opening the valve, F, the gun can be worked in the ordinary manner. Fig. 2 represents an end view of the carriage and slide. Besides the advantages which this plan offers for working heavy guns with very few men-thus enabling merchant vessels to provide themselves with heavier and more effective armaments-it is contemplated that the reception of the shock of explosion on the elastic nature of the vacuum, or its counter force, will prove very beneficial to the ship's side, and be a subject for special consideration. tated to the bottom of the shaft when the rope or chain breaks; in this case the apparatus is self-acting. 2. From either the men or load being drawn over the pulley; in this case also the apparatus is self-acting. The apparatus is readily applied to the present guides now in use, whether they are of wood, iron rods, or chain, and may be attached to the cage in a few hours. By reference to the prefixed sketch it will be seen that the apparatus is fastened upon the guides by the rope being represented as broken, but when the rope or chain is tight, and the cage in work, the levers are raised on their fulcra, and lower the wedges in the tapered shoes, which slackens them on the guides; and when the rope or chain becomes broken or detached, the levers drop and raise the wedges into the tapered shoes, and consequently grip the guides firmly on both sides, so that the greater the weight in the cage, the tighter the wedges hold.— Mining Journal. LAW OF PATENTS.-AMERICAN CASE. Blanchard's Gun-Stock Turning Lathe. Opinion delivered by Judge Kane in the United States Circuit Court in the case of Blanchard v. Eldridge, on a motion for attachment because of a breach of injunction-for an infringement of Blanchard's Gun-Stock Turning Lathe as applied to turning Shoemakers' Lasts, March 8, 1849. The patent right of Mr. Blanchard has been the subject of examination before me in two trials at law, the present defendant being a party. Although no verdicts were rendered, I was fully satisfied by the evidence, that the patent was a highly meritorious one, of ancient date, and that the defendant had violated it. I did not besitate, therefore, to grant an injunction against him, upon the proper proceeding being instituted in equity. This injunction being still in force, the defendant has devised a new machine, and is now using it, as the complainant asserts, in violation of the injunction. The question is thus presented, whether the new machine of the defendant infringes the complainant's patent right? In my charge to the jury on the other side of this court, I spoke of Mr. Blanchard's machine as follows:-"It is a turning machine, capable of producing with rapidity from the rough material, by a single operation, an irregular form, similar or proportional in all respects to a given model. It consists essentially of a model, revolving in contact with a friction tracer, while the rough material revolves, with the same velocity, in like contact with a rapidly moving cutter-wheel; either the model and material, or else the friction tracer and cutter wheel, having a progressive lateral motion, so that by the revolutions of the model and material all the points of their respective surfaces are presented in succession to the touch of the friction tracer and the action of the cutter-wheel respectively; that is to say, all the points on the surface of the model successively to the touch of the tracer, and the corresponding points on the surface of the material to the action of the cutter-wheel. Its value consists in this, that it combines the accurate imitation of a slowly-revolving model with the rapid action of a cutter-wheel. Its principle is the combination of the cutter-wheel, model, and friction tracer, with the arrangement for effecting the lateral motion." Between this and the respondent's present machine there appears to be but a single point of difference. "The peculiar novelty of the respondent's machine, according to the report of the Commissioner, William W. Hubble, Esq., appears to be in the formation, suspension, and manner of propelling the cutting instrument, to shape the last from the rough block without finishing. The cutting instrument consists of a double-edged curved knife of about the same curve or periphery as the friction column; it is bolted to a perpendicular iron bar, about an inch square, which plays up and down between and through two iron straps, fastened to the main transverse carriage. This cutting instrument receives its motion from a pitman, attached to a crank, put in very rapid revolution, and thereby with great velocity moves the cutting instrument in a straight perpendicular line up and down, which being sharp on both the upper and lower edges, in passing the rough material, cuts it both in its ascent and descent. Attached to the crank shaft are a fly-wheel and a balance weight." The two machines, then, have the same object; and they attain it by the same means, operating in the same manner, except that Mr. Blanchard's cutters are set on the periphery of a wheel, and act in the curved line of its motion, while in Mr. Eldridge's the circular motion is transferred to a shaft, and the cutters, being affixed to this, act with an alternating movement in a right line. It is not contended that the shaft is an improvement on the wheel, that it is more economical of structure or use, or that it does its work more effectively or rapidly. On the contrary, it is evident that, if well made, it must be more costly at first, that it must exact the expenditure of more power in working, must do the work less rapidly and less perfectly, and must be less durable. The only question to be decided is whether it differs in principle, or by a modification of details merely, a substitution of equiva LAW OF PATENTS.-AMERICAN CASE. lents-whether, in a word, it is or is not an evasion of the complainant's patent. I have heretofore spoken of the principle of the patented machine, as involving the combination of a cutter-wheel with certain other parts. This language was sufficiently accurate, perhaps, for the purposes of the occasion, since there was then no controversy regarding a machine without a cutterwheel. But it was rather a description of Mr. Blanchard's machine as in use, than a definition of its principle. The patentee evidently had a broader view of his invention. In his specification he says, " Moreover the cutters may be made sharp on both edges, and the cutter-wheel may be made to turn a quarter of a circle or less, backward and forward, and so the cutters be made to cut by both edges; but the continued circular movement is believed to be preferableto any other." Now, when the cutters are acting with this alternate or reciprocating motion, they can scarcely be considered as moving on a cutter-wheel, implying, as this does, the idea of continuous rotation. The abstract principle, therefore, that shall include both forms of structure, cannot recognize the cutter-wheel, strictly speaking, as an element of the combination-but rather a cutter, or series of cutters, deriving motion from a circle, and acting in a circular arc. If this were the correct definition of Mr. Blanchard's principle, the difference between the two machines would be resolved very easily. One, the patented, applies the revolving power immediately to its work, in the most simple, convenient, economical, and effective mode;-the other, the defendant's, interposes between the revolving power and the work an additional member that serves no purpose whatever, unless to avoid identity with the patented machine. The patent law would give but an illusory protection to the meritorious inventor if it respected devices like this. It requires of a patentee that he shall disclose in his specification the most beneficial mode of applying his principle that is known to him. (Neilson's patent, Webster Ca., 337.) But it does not require of him to go further, and point out all the possible contrivances by which the machine that illustrates his principle can be rendered less beneficial or less perfect. The more fully matured his discovery, the more complete his machine in all its parts, the more signally and immediately profitable to the community, the greater will be the number of the defects it has avoided or provided for, and the greater, of course, the number of changes for the worse that may be grafted upon it by a froward ingenuity. For surely ingenuity may be so styled, when it toils with inverted energies, not to improve or advance, but to devise something less useful and more costly than But, in truth, the principle of Mr. Blan- Now although it be true that, technically speaking, an inventor cannot claim a patent for the principle he has discovered, yet it is equally true that, if he has embodied it in any clear, definite, and distinct form, others will not be permitted to take that principle and embody it in some other form merely copied from his; "And thus," as was well argued in the case I have cited, "you may attain a result which is practically equivalent to the patenting of a principle;" for when you have put your intention into shape, no person will be allowed to come in and steal the spirit of your invention by putting it into some other shape, which, though different, is imitated from yours. The defendant in this case has mistaken his legal rights, and the sooner he is advised of his error, the better for him and for the public. He is obviously possessed of considerable mechanical ingenuity, which, if applied in a different direction, may advance his own interests, while contributing inciBut he has dentally to the interests of art. confounded the details of Mr. Blanchard's machine with its principle; and in seeking to escape from the operation of the patent, he has violated the law by which it is guarded. It is possible that he may have been misled by the language of the charge, when his case was before me on the law side of the court. Abstract propositions are liable to inaccuracy, when elicited in the haste of a trial at bar; and however accurate, they are not suited to the purpose of imparting instruction to a jury. I prefer, therefore, generally to employ illustrations, derived from the case itself, to convey the legal principle which should rule it, rather than to announce the law in general and abstract terms. It is enough for me if I can succeed in teaching all that belongs to the cir. cumstances and the time. |