
    SOCIÉTÉ ANONYME DES ANCIENS ÉTABLISSEMENTS CAIL v. THE UNITED STATES.
    [No. 18796.
    Decided December 2, 1907.]
    
      On the Proofs.
    
    The invention is for a gas check or obturator, a device indispensable to the effective operation of breech loading cannon. The first claim in the patent is for a “ yielding packing ring of asbestos and tallow;" the third claim includes a specification of construction and utilization. The Government with the assent of the inventor manufactures such gas checks consisting of a yielding packing- ring of asbestos and tallow, but by somewhat different means than those covered by the third claim. The defendants insist that the invention includes the employment of the other elements, and that they constitute an integral part of and are inseparable therefrom.
    I.It is well settled that where there was an invitation to present the details of a patent to the Government and an examination by a board of officers and a user by the Government without claim of ownership, a contract must be implied and the court must assume jurisdiction.
    II.The specifications and claims in a patent being addressed to those skilled in the particular art or science, only such precision and nicety of description will be required as will enable such persons to use the invention.
    III. When the device consists of a yielding packing ring of asbestos and tallow and every description in the patent imports a predominance of the one central idea of a yielding packing composed of asbestos and tallow, it is the invention; the details of construction are of minor importance.
    IV. The nonessential details of construction found in the specifications and claimed in a patent should not be allowed to obscure the real invention.
    V.Courts generally have extended to inventors the protection of the patent laws when the real invention is susceptible of ascertainment, and the inventor has contributed a new and useful invention to the art.
    VI.Such narrow limitations should not be imposed upon the patent as will enable subsequent inventors to use the invention with impunity by appropriating the essential element of the device, i. e., the indispensable, functioning feature of it.
    
      The Reporters’ statement of the case:
    The following are the facts of the case as found by the court:
    I. On June 12, 1883, Charles T. M. Valérand de Bange, a Frenchman, filed in the United States Patent Office an application for a patent for breech-loading ordnance. The specification was the same as in the patent when ultimately granted, but the claims read as follows:
    
      “ First. The screw-plug B, pin N, head N', and yielding packing M, in combination with each other, and with the gun A, arranged to serve as herein specified.
    “ Second. The locking ring G8, pin N, head N', and packing M, in combination with the screw-plugs B, and gun A, as herein specified.
    
      “ Third. The construction of the packing M with a fibrous interior M', and the shells M2 and M3, in combination with the pin N, head N', screw-plug B, and gun A, as herein specified.
    “ Fourth. The door G, turning in the axis F, in combination with the gun A and screw-plug B, and arranged to support the latter, and allow it to be moved backward and forward through the door, as herein specified.
    
      “ Fifth. The turning-catch H, in combination with the door Gr, gun A and screw-threaded plug B, arranged to engage its arms alternately with the gun, and with the screw-plug in the several positions, as herein specified.
    “ Sixth. The lever D, having a projection or cam D', in combination with the door G, having a groove g, and with the screw-plug B and gun A, as herein specified.”
    The examiner rejected all the claims for the following reasons:
    “ Claims 1, 2, 3, 5, and 6 are vague. The arrangement of the parts should be defined in the claims, not left to be discovered from the specification. Claims 1 and 2 are met by the patent of Quick, No. 258116, May 16, 1882, ordnance breechloaders, ordnance.
    “ Claim 4 is met by the patent of Palliser, No. 221419, November 11, 1879, breechloaders, ordnance.”
    Thereupon De Bange’s attorney amended all the claims, the amended claims 1 and 3 reading thus:
    “ 1. The screw-plug B, pin N, head N', and yielding packing M, in combination with each other, and with the gun A, arranged to allow the head to be driven rearward and compress the packing as herein specified.
    “ 3. The packing M having a tough, yielding interior M' in combination with the elastic shells M2 and the rigid shells M8, adapted to serve with the pin N, head N', screw-plug B, and gun A, as herein specified.”
    The examiner rejected the first four of the amended claims for these reasons:
    “ The first two claims do not distinguish the construction of applicant’s breech-closing mechanism. The relative location and operation of the parts must be set forth.. Claim 3 is for a species of packing — a distinct invention — which must be covered in a separate application. The fact that applicant in his claim describes the packing as adapted to “ serve ” with other elements does not free the claim from the objection raised. Claim 4 is met by the patent of Yavasseur, No. 275550, April 10, 1883, ordnance, breech-loading.”
    
      Thereupon De Bange’s attorney canceled claim 4, and amended claims 1, 2, and 3 so as to make them read thus:
    “ 1. The partially threaded plug B, headed pin NN', extending through said plug, and the yielding packing M, arranged between the head N' and the inner end of the plug, in combination with each other and with the gun A, arranged as shown to allow the pin to be driven rearward and compress the packing, as herein specified.
    “ 2. The locking ring G, turning like a door on the hinge F, screw-plug B, and headed pin NN', extending through said plug, in combination with the packing M, arranged between the head N' and the inner end of the plug and the gun A, as herein specified,. for the purpose set forth.
    “ The packing M, having a tough yielding interior M', the elastic shells M2, and the rigid shells M3, in combination with the pin N, head N', screw-plug B and gun A, as herein specified.”
    The examiner objected that—
    “ Claim 3 does not identify the construction. The relation of the packing to the pin and plug, and of such parts to the gun, should be set forth in the claim.”
    Thereupon De Bange’s attorney amended claim 3 so as to make it read thus:
    “ The packing M having a tough yielding interior M', elastic shells M2 and rigid shells M3, arranged between the inner end of the screw-plug B and inner surface of the head N' of the pin. N, in combination with such parts B, N, and N1, and the whole arranged and serving relatively to the gun A, as and for the purposes set forth.”
    After this last amendment the patent was granted, reading as follows:
    “ United States Patent Oeeice.
    “ CHARLES T. M. VALERAND DE BANGE, OP PARIS, PRANCE, ASSIGNOR TO SOCIÉTÉ ARONTME DES ANCIENS ETABLISSEMENTS CAIL, OP SAME PLACE.
    “ BREECH-LOADING ORDNANCE.
    “ Specifications forming part of letters patent No. 301220, dated July 1, 1884.
    “ [Application filed June 12, 1883. (No model.)]
    
      “To ail whom it may concern:
    
    “ Be it known that I, Charles Timothée Maximilien Valérand de Bange, of Paris, in the Republic of France, have invented certain new and useful improvements in breech-loading guns, of which the following is a specification.
    “ The improvements apply to breech-loading cannons which employ a screw-plug having its threads interrupted.
    “ I have devised a system of packing placed in advance of the plug, and which is expanded by the force of the explosion of the powder to make a tight joint to prevent the leakage of gas. I also employ a lever which performs two important functions — one to aid in turning the plug, and another as a safety-guard to insure that the breech is reliably closed before the piece is discharged. My system requires no special tools or apparatus for the opening and closing.
    “ The accompanying drawings form a part of this specification, and represent what I consider the best means of carrying out the invention.
    “ Figure 1 is a central longitudinal section. The strong lines show the parts ready for firing. The dotted lines show the transverse lever in a position for conveniently operating to turn the screw-plug. Fig. 2 is a rear view showing the parts locked. Fig. 3 is a corresponding view showing the parts unlocked. The dotted lines show the breech mechanism swung around so as to leave the breech entirely open. Fig. 4 is a longitudinal section' showing the screw-plug partially moved toward the rear. Fig. 5 is a corresponding section partly in elevation, showing the screw-plug moved far to the rear, ready to be carried around by turning on the hinges of the inclosing-collar. Figs. 6 and 7 represent the packing ring detached. Fig. 6 is a face view, and Fig. 7 a section in the plane of the axis. Fig. 8 shows what I term the “ turning-catch ” on a larger scale.
    “ Similar letters indicate like parts in all the figures.
    “ A is the rear portion of the body or barrel of the gun. B is a screw-plug having its threads interrupted.
    “ C is a door in the form of a ring or collar, larger than the bore, strongly hinged to the body A on one side, and adapted to swing open when required. When closed, it sinks into a depression surrounding the bore at the breech.
    “ The interior of the breech of the gun is equipped with series of partial screw-threads alternating with longitudinal spaces, in which the screw-threads are cut away, and allow corresponding segments of screw-thread on the plug to be moved inward and outward easily when the plug is turned in the right position. By thrusting the screw-plug in as far as may be by a direct thrust, and then giving it a partial revolution, the screw-plug is strongly engaged with the breech of the gun. A reverse motion liberates it. D is a lever extending across in rear of the screw-plug B, and hinged thereto by the pivot Q in the short arm B'.
    
      “ I employ a locking-catch turning on a center, and subject to the force of a spring, T, which tends to turn it always in one direction. It performs important functions. It is marked H, certain portions being designated, when necessary, by additional marks, as H' H2. It turns on a center, h, fixed in the door or hinged ring G.
    “A liberal hole in the line of the axis of the screw-plug B carries a stout sliding pin, N, at the extreme front of which is a stout head, N'. The portion of the body adjacent to the head N' is slightly enlarged. The head N' is adapted to receive the force of the powder at the discharge. At the moment of the discharge this head moves backward, compressing a relatively soft and expansible packing-ring, M, behind it. Certain portions of this ring will be distinguished, when necessary, by additional marks, as M' M2. The body M' of this packing is of asbestus saturated with tallow, and affords a sufficiently yielding mass with the required capacity for enduring heat and for withstanding the very strong compressive force to which it is subjected by the discharge. It is inclosed between two thin shells, M2 M2, of copper, one fitting the body M' on the inner and the other on the outer side, and nearly incasing the entire packing. Both the body M' and the copper M2 are then inclosed between two strong shells of brass, M3 M3. The entire packing thus made is adapted to maintain its form, but to allow a small amount of radial expansion sufficient to pack the joint tightly against the escape of gas. This expansion is due to two causes — the tapering form of the front end of the pin N, which acts on the interior of the packing, and the powerful compression received from the head N'. The expansion from one or both causes is sufficient to depress the exterior of the copper M2 tightly against the interior of the gun, thus effectually preventing any leakage of gas.
    “ Let us observe the succession of the several movements. To open the breech after firing I proceed as follows: I elevate the cam-lever D into the position shown in dotted lines in Fig. 1. This brings the head or cam D' out of the mortise g; and I then turn the screw-plug B from right to left about one-sixth (£)' of a revolution, the movement being limited by the stop e. (See Figs. 2 and 3.) During this movement the wedge form of the groove b acts on the arm IT, forcing it out of the groove. This causes a partial revolution of the turning catch H on its axis h, and engages the arm H2 in the mortise a of the breech. The screw-plug B is now free to be drawn bodily outward; but the engagement of the arm FI2 in the breech compels the door G to remain immovable. So soon as the screw-plug B is drawn out sufficiently, the mortise b in the screw-plug is presented to the arm FI', and the catch H, under the influence of the spring T, turns a little on its pin h and engages the arm IT in said mortise. This locks the screw-plug B and the door G firmly together, and by the disengagement of the arm H2 from the mortise a in the" breech allows the door G, carrying the screw-plug B, to be turned on the axis F, leaving the breech entirely open. This position is represented in dotted lines in Fig. 4. If there be any considerable adhesion of the packing M to the interior of the gun, it may be difficult to draw the screw-plug endwise. In such case, before drawing out the screw-plug, I pull down the lever D into the position shown in strong-lines in Fig. 4. This causes the head D' to strike on a high part of the door G, and acts camwise with great force to induce a small endwise movement of the head N' and packing M sufficient to overcome the adhesion. Then the plug-may be easily drawn out by a direct pull, as before described. To close the breech again after a fresh cartridge is introduced, I operate in the reverse manner. I turn the door G on its axis F, carrying therewith the screw-plug B until the door is closed against the breech of the gun. This closing movement causes the arm H3 of the turning-catch FI to strike the inclined side u of the recess U, formed in one side of the breech, and to thereby turn the catch H against the force of the spring T. This turning of the catch H takes the arm IT out oi the mortise b' in the screw-plug B, and leaves the latter free to be pushed forward. I then push the screw-plug forward into the gun. Next I turn the screw-plug from left to right a sixth of a revolution, the movement being limited by a stop, <?', which is a shoulder or offset formed on the door. Now the lever D drops by its gravity, assisted, if necessary, by the force of the hand, and its cam D' enters the mortise g in the door. This makes sure that the closing is complete, for if the screw-plug has not been turned sufficiently the head D' of the lever D will not enter the mortise.
    “ Modifications may be made in the forms and proportions. Parts of the invention may be used without the whole.
    “ I claim as my invention—
    “ 1. The partially-threaded plug B, headed pin N N', extending through said plug, and the yielding packing M, arranged between the head N' and the inner end of the plug, in combination with each other and with the-gun A, arranged as shown, to allow the pin to be driven rearward and compress the packing, as herein specified.
    “ 2. The locking-ring G, turning like a door on the hinge F, screw-plug B, and headed pin N N', extending through said plug, in combination with the packing M, arranged between the head N' and the inner end of the plug and the gun A. as herein specified, for the purpose set forth.
    
      “ 3. The packing M, having a tough yielding interior, M', elastic shells M2, and rigid shells M3, arranged between the inner end of the screw-plug B and inner surface of the head N' of the pin N, in combination with such parts B, N, and N', and the whole arranged and serving relatively to the gun A as and for the purposes set forth.
    “ 4. The turning-catch H, in combination with the hinged locking ring or door G, gun A, and partially screw-threaded plug B, arranged to engage its arms alternately with the gun and with the screw-plug in the several positions, as herein specified.
    “ 5. The lever D, having a projection or cam, D', in combination with the locking ring or door G, having a groove, g, and with the partial-threaded screw-plug B and gun A, as herein specified.
    “ In testimony whereof I have hereunto set my hand, at Paris, France, this 28th day of May, 1883’, in the presence of two subscribing witnesses.
    “ CHARLES TlMOTHÉE MaXIMILIEN VaLERAND DE BaNGE.
    “ Witnesses:
    “Edward P. MacLeaN,
    “ Eug. Dubail.”
    The state of the art at the time this patent No. 301220 was applied for is shown by a number of prior patents and publications: United States patent No. 6612, of 1849, to Chambers; United States patent No. 9943, of 1853, to Schenkl; United States patent No. 13507, of 1855, to Joslyn; United States patent No. 14949, of 1856, to Clement; British patent No. 907, of 1861, to Bailey; British patent No. 3478, of 1862, to Richards; British patent No. 1415, of 1856, to Lindner; British patent No. 3275, of 1863, to Lindner; British patent No. 3308, of 1863, to Byrnes and Benjamin; United States patent No. 60832, of January 1, 1867, to Chassepot; French patent No. 91107, of December 1, 1870, to Mauduit; United States patent No. 159170, of January 26, 1875, to Felt; United States patent No. 258116, of May 16, 1882, to Quick.
    Another invention was the Williams gun, used in the Confederate army.
    The Elswick cup gas check and the Broadwell ring gas check had each been in successful use in connection with the slotted screw breech plug for some years before de Bange’s gas check was made.
    
      The history of the development of gas checks using a yielding packing, is contained in an article in volume 12, of the Revue d’Artillerie, an official publication of the French Government, pages 393-398, 402-415, and volume 13, pages 18-24.
    The evidence discloses that none of the foregoing inventions used or employed a plastic pad composed of asbestos and tallow.
    The automatic sealing of the breech of a gun by the radial expansion of yielding packing, under the axial pressure of the head of a movable pin, driven rearward by the powder gases, was successfully accomplished in small rifles by the Chassepot invention, described in his patent No. 60832. The three layers of rubber which compose the packing are concentric rings, the outer ring being the one which actually seals the breeech. This gas check was adopted for the French army rifle in 1866, and was the regulation type until (after the Franco-German war) the metallic cartridge was substituted, dispensing with the need of a gas check in the gun itself.
    The evidence discloses that the above invention was nor successfully applied or used in field guns or cannon of large caliber, and is not now so used.
    [Erom the “ Revue d’Artillerie,” vol. 13, p. 18.]
    “EXPERIMENTS WITH OBTURATORS.
    “ Colonel Olry made trial in 1868 at Versailles of cup ob-turators of pasteboard covering the head of the cartridge.With these cups, with or without a copper ring, the obturation was perfect in firing heavy charges; only it was necessary to find the means of withdrawing these cups after the charge had been fired. Different methods were proposed.
    “ It was attempted to extract the cup, either after firing by means of a hook in the form of a T, or automatically by forcing it to incrust itself by the very pressure of the gases upon the face of the breechblock, which for this purpose, had cut into it square cavities, which were exactly reproduced in the cup itself.
    “ None of these methods having completely succeeded, the cups were abandoned, not only because of the difficulties which their extraction presented, but still more because of the impossibility which was found of using them in the firing of light charges.
    “ It is at this time that it was sought to apply to ordnance the mode of obturation then in use for the Chassepot gun. Commandant de Montluisant made trial at Versailles of rubber obturators. The first trials gave results satisfactory enough to follow them with experiments at Chalons and at Gavre. Rings were used, the center one being made of vulcanized rubber, very supple, covered only partially by layers of rubber of increasing hardness.
    ’ “These rings were tried at Gavre in a cannon of 24 c. They were supported by a movable head like that afterwards adopted for the Olry cannon. But the supple rubber, which was not covered in all parts by the harder rubber, forced itself into the smallest joints, and the obturators, although efficacious, were destroyed at the end of a few shots by loss of material.
    “ Commandant de Montluisant, having quitted the Atelier de Precision, Captain de Bange continued the study of the question.
    “ When, in May, 1872, the experiments with the Olry cannon were begun, the first guns tried — that is to say, steel cannons Nos. 3 and 4 — were fitted with a rubber obturator in the style of those which before the war had given the best results. They were formed of a ring of supple rubber between two plates of hard and resistant rubber.
    “ The use as an obturator of a matter as elastic as rubber required that the dimensions of the obturator and those of its lodgment should be determined with the greatest precision. Captain de Bange thought that, if a nonelastic substance was used to form the obturators, so great a precision would not be necessary. Consequently, he proposed for the Olry cannon obturators of soap, which were tried in competition with those of rubber.
    
      “Rubber obturators. — In regard to rubber obturators the commission had occasion to verify anew facts analogous to those .which had already been observed in the preceding experiments, that is to say:
    “ With steel cannon, rupture of a movable head, attributed to an oblique blow resulting from differences in the elasticity of the rubber in different points of its surface; separation of the different washers composing the obturator.
    “With bronze cannon, rearward spreading of the rubber as soon as the chamber began to be deformed.
    “ The commission, however, reported that with rubber ob-turators the working was always easy, the elasticity of the material restoring the obturator to its primitive form as soon as the shot had been fired.
    
      
      
    
    
      
      “ Soap obturators. — The soap obturators proposed by Captain de Bange for the cannon Nos. 3 and 4 were of two sorts.
    “ One sort was composed of a washer of soap placed between two cups of molded leather. The cup, placed on the movable head, was protected from the action of the gases by a disk of thin brass, 0 mm. 2 in thickness. A metallic split ring placed on the opposite side held the edge of the leather at the height of the junction with the movable head. The soap used was ordinary white soap.
    “In the other kinds the cups of thin brass of 0 mm. 3 in thickness replaced the leather cups. The soap employed was an olive-oil soap with an alkaline base.
    “ These obturators, which are the first obturators of plastic substance adopted by Captain de Bange, did not give satisfactory results. Under the influence ox heat the soap became soft and ran between the walls of the chamber and the head of the breechblock.
    “ To escape from the inconveniences which resulted from this failure of consistence, Captain de Bange thought to place the soap in an envelope designed to cover it altogether. The obturators so constructed were employed in bronze cannon, then later in steel cannon Nos. 5, 6, and 1.
    
    “ But the envelopes of serge, linen, or copper — that is to say, combustible envelopes — were soon burned, and, the soap being laid bare, the same inconveniences occurred as with the unenveloped obturators.
    “ Envelopes of lead, although incombustible, gave no better results. It happened sometimes that the lead, on account of its great inertia, rose up on the forward cup, which laid the soap bare and tended to make the action of the screw difficult.
    “ The cups of thin, soft metal between which the soap was held were themselves capable, by crushing and fastening themselves against the walls of the chamber, of occasioning difficulties in the working, although nothing of that sort was observed with obturators with leather cups. These latter cups, however, did not seem to have a sufficient resistance, for in the firing of cannon No. 5 the forward cup of soap obturator was pierced and the soap laid bare against the movable head.
    “ Ordinary soaps having too great a fluidity, Captain de Bange proposed successively as a plastic obdurating material :
    “ Soap with a base of lime, a gritty substance and but little plastic, which did not give very good results;
    
      “ Lead, which resulted in clogging and in inadmissible difficulties in the working;
    
    “A mixture of talc and tallow, which presented the same inconveniences as the soap formerly used;
    “ Finally a mixture of tallow and asbestos.
    “ The first obturator in tallow and asbestos was tried with the Olry cannon No. 6 August 20, 1873.
    “ It was composed of seventy parts of asbestos to fifty of tallow. The plastic ring, held in place by a linen envelope, was kept between two cups of tin. Copper split rings protected the edges of the rear cup; the forward cup had none. In order to prove the resistance of this obturator it was subjected to several rapid firings. It always acted well.
    “ Since that time only the mixture of tallow and asbestos has been used as a plastic material, and investigations have only been directed to secondary points, such as the best proportion of grease to be used and the greater or less expediency of fitting the forward cup with a copper split ring. A pressing back of this, ring on the movable head was feared, an inconvenience that had been observed with the thin brass cups.
    “ But these last investigations belong to subsequent series of experiments in testing the Olry cannon. They will not be discussed here.
    “ In its report of November 4,1873, the commission agreed that a good obturation was obtained in a practical and durable manner with the obturators of asbestos and grease. The committee, admitting this conclusion, thought that one could thenceforth consider the obturator of asbestos and tallow, with cups of tin, as a satisfactory solution for field pieces. The experiments carried on since that date have •completely justified this verdict.
    
      “Movable head. — In the beginning the bronze cannon of the Olry system had movable heads of rectangular section. The steel cannon Nos. 5, 6, and 7 had the same shape. The tests to which these cannon were submitted showed that it often happened that dirt, adhering either to the movable head or to the walls of the chamber, lodged between the two and rendered the working very difficult.
    “ This inconvenience was remedied by rounding the movable heads and giving them what is called a mushroom form.
    “ Berger proposition. — Captain de Bange, when noting in the month of November, 1872, in a paper on obturators, the inconveniences to which elastic obturators had given rise during the experiments at Chalons and at Versailles, thought that they might have been avoided by an initial compression given, to the obturator. But he added that it had not been done in order not to complicate the breech mechanism.
    “ Captain Berger, more impressed doubtless with' the inconveniences due to elasticity in the rubber obturators than to those resulting from an over complication of mechanism, proposed a mode of initial tightening for those obturators.
    “ The application of this was made to the Olry bronze cannon No. 1, whose chamber had become enlarged, and in which obturators, whether of rubber or of soap, deteriorated rapidly.
    “ The stem of the movable head was lengthened so as to extend.right through the breech screw and to be freely moved. The extremity of the stem, threaded, received a nut fitted with a handle. A longitudinal groove in which a guide moved prevented the stem from turning in its lodgment when the nut was screwed down to compress the obturator.
    “ The experiments took place in October, 18TB. Some charges fired with obturators of talc and with obturators of rubber of ordinary thickness gave rise, in spite of the preliminary pressure, to habitual accidents, losses of material, ruptures of movable heads.
    “A curious fact may, however, be related. In increasing the thickness of the washer and in carrying it to 40 milli-metres, a system of obturator was obtained which worked with regularity, although the gun was notably swollen.
    “A washer of this thickness resisted perfectly in a series of experiments executed with a charge of 1,800 grammes of powder A 1 (Vo=500 metres), although the cannon burst at the 249th discharge. One may notice here the good results which were obtained at that time with the movable head with a long stem, to which Captain Berger had recourse to try his process of initial tightening.
    “ To sum up: If the de Bange obturator solved the question of obturation in the case of guns of a sufficiently invariable profile, the Berger system, more complicated, it is true, might be a solution for guns whose chamber is exposed to getting out of shape.”
    III. The requirements to be met by the gas check of a large gun are of a very severe character. It is subjected to pressures of from 30,000 to 40,000 pounds per square inch, to very high temperatures, to the effects of corrosive gases, and to the effects of repeated and violent shocks. The determination of a material or composition of matter capable of performing with requisite certainty the function of sealing the breach, and capable also of resisting without impairment the effects of the powder explosions, and which should not get out of order by reason of the concussions and high temperature to which it is subjected in action, and which should form, with the other elements of its breech mechanism, an operative combination or mechanical organism, presented many and difficult problems, the solution of which necessarily required practical test and demonstration under actual service conditions.
    IY. The de Bange obturator was brought to the attention of the United States ordnance authorities on April 27, 1883, at which time the United States naval attáché at London, then Lieut. Commander F. G. Chadwick, forwarded to Lieut. Commander William M. Folger, of the Bureau of Ordnance, Navy Department, a detailed description of the de Bange gas check as it then existed, together with the following description of its method of making, furnished by the inventor, de Bange:
    [Translation of tlie description of the method of making gas checks, as given in Lieutenant Chadwick’s letter.]
    “ The asbestos should be of the best quality and free from extraneous matter. It is pulverized and passed through a sieve. The tallow is put in a pan and heated until it begins to steam. The asbestos is then poured in and thoroughly mixed in by means of a wooden spatula. The proportion is by weight.
    “ When the material has been made homogenous, it is compressed in a mould similar to that used for rings of compressed powder. The edges are rounded, and then the cake is weighed, the proper weight having been previously fixed. The cake is then covered with cloth. For that purpose bands of cloth are cut to a suitable breadth, and the ends are joined so as to form cylinders which are placed inside and outside of the cake, and whose ends are sewn together after they have been cut with scissors, so as to fit more easily.
    “ The cups are formed of bands of laminated tin, whose thickness varies according to the caliber. The disks are cut out with a punch and then shaped by dies and moulds, care being taken that the thickness be diminished as little as possible at the angles, which should be rounded in this first stage of their manufacture. After being shaped, each disk is put on the lathe, the edges are trimmed to the proper height, then chiseled off inside.
    “ The rings are made of brass wire drawn through a gauge and not annealed, in order to preserve all the elasticity due to the cold hardening. The cross section of the rings is in the form, of a right-angled triangle, but rectangular wire must be used to facilitate tbe winding. The last operation takes place on a reel by means of a cylindrical iron mandrel, on which the thread, whose end has been bent back at a right angle, is kept in place by the aid of a collar and a thumbscrew. As the mandrel turns it pulls strongly on the wire, and in this way one obtains a spiral spring whose coils touch.
    “ This spring changes its diameter when relaxed. It is then placed on another mandrel, also of iron, but larger than the first one, and the coils pressed down and joined together with soft solder. After being so arranged, this spring is cut on a helix whose pitch is so adjusted that the bevels made on each coil have a proper length, and moreover when the ends are brought together the exterior diameter is greater and the interior diameter smaller than in the finished ring.
    “After the coils have been cut, the bevels are polished smooth. If there is room, the rings are rounded and soldered in order to place them on the mandrel.
    “ When all the elements are prepared, they are pressed together. The tools required include, first, a conical matrix of steel of the same shape (inclination) as the seat of the obturator, but of a little smaller diameter; second, a movable head of hard brass or steel like that of a cannon, but shorter and flat on top; third, a flat steel washer; fourth, a brass plug on which the pressure is exerted.
    “ First the movable head is placed at the bottom of the matrix, the wider end of which should be on top. Then the front ring, the front cup, the cake covered with cloth, the rear cup, and finally the two rear rings are successively put in place. On the top of all are placed the washer and the plug, and a heavy pressure is put on them. Each one of the elements takes its place, and the rings are lodged in the cups, the tin of which covers them lightly and keeps them in this position.”
    On July 5,1888, Lieutenant Chadwick wrote the following-letter :
    “ LONDON, England, July 5,1883.
    
    
      “ Sir : I have the honor to forward herewith a de Bange ‘ obturator,’ which was kindly presented on request by the French minister of war.
    “ I am, very respectfully, your obedient servant,
    “ F. E. Chadwick,
    “ Lt. Oomdr., U. S. Navy, Naval Attache.
    
    “ Commodore J. G. Walker,
    
      “ XJ. S. Navy, Chief of Bureau of Navigation,
    
    
      Navy Department, 'Washington.'''1
    
    
      Y. In 1883, by act of Congress approved March 3, 1883, a board was constituted known as the “ Gun Foundry Board,” composed of eminent officers of the army and navy, headed by Near-Admiral Simpson, U. S. Navy, whose duties, among others, were to report on the establishment of a Government foundry, “ or what other method, if any, should be adopted for the manufacture of heavy ordnance adapted to modern warfare, for the use of the Army and Navy of the United States.”
    In the official report of this board reference is made to a visit to the claimant’s works at Paris, France, on August 29, 1883, and to the inspection by said board of the de Bange system of ordnance. In the said report of said board is the following:
    “ Breech fermeture. — All the French guns are breech-loading, and are fitted with the interrupted screw system, as modified by Colonel de Bange to suit his gas check.
    “ Gas check. — ‘ The de Bange gas check ’ is universally employed.”
    In the proceedings of the United States Naval Academy for 1884, Yol. X, No. 4, is an account of the proceedings of the Gun Foundry Board while abroad, and at pages 148-752 is a description, illustrated by plates, of the de Bange invention.
    YI. About the year 1884 the ordnance officers of the United States Navy Department began experimenting with the de Bange gas check. As a result of all the investigations and trials the de Bange obturator was adopted by the United States military and naval authorities, and all its heavy ordnance (5-inch caliber and upward) have been of that type since about 1885. Since the adoption of the de Bange gas check no gas checks of other types have been used in the service of the United States.
    The United States Government has never disputed the title of claimant’s assignor, Colonel de Bange, as inventor of the said invention; but, on the contrary, the said invention has, ever since its adoption, been known in the service of the United States as the “ de Bange gas check,” and is described by that name in the official reports of the Secretaries of War and of the Navy. The United States has used claimant’s patented invention knowingly, with tlie patentee’s consent, and without claim of adverse right.
    VII. The de Bange obturator is described and its advantages discussed in many technical publications and official reports.
    In Lieutenant-Commander Ingersoll’s text-book on ordnance in use at the United States Naval Academy (ed. 1894), after stating the conditions which a breech mechanism should fulfill, he says:
    “ The interrupted screw system combined with the de Bange gas check has been adopted for use with the B. L. B. guns for the navy, as fulfilling the above conditions so far as there is any possibility of their being fulfilled at all.”
    And further—
    “ The advantages of the de Bange gas check are certainty of action, durability, and ease of adj ustment. It requires no great accuracy of workmanship or care in fitting, and it may be changed in case of accident with little delay.”
    In Captain Metcalf’s text-book in use at West Point Military Academy (ed. 1894) is the following:
    “ The Broadwell ring has to seal four surfaces not protected from, dirt instead of but two, and the joint most difficult to seal is that which is most exposed to dirt.
    “ Of the attached gas checks the Freyre, being inorganic, is less subject to extreme variations of temperature; it also takes up less room in the thickest part of the gun. It is open to the objection that a slight nick on the edge of the ring might render the entire apparatus worthless.
    “To the last consideration is due the almost universal employment of the de Bange gas check, since this has been found almost indestructible by the accidents of service and to resume its shape when deformed in the firing.”
    Also, in the Scientific American for June 17, 1898, describing the “ Navy rapid-fire gun,” is the statement that—
    “ There have been no cartridge cases as yet for the 6-inch quick-firing gun, the de Bange gas check being used for obturation.”
    In Engineering, an illustrated weekly journal published at London, for April 29, 1892 (Vol. LUI, p. 518), in an article entitled “ Modern United States artilllery,” occurs the following passage:
    
      “ Numerous methods have been tried at various times for closing the breech of guns, but at the present time the number has practically been reduced to two — the Krupp, or sliding-wedge system, and the French, or interrupted-screw system. Between the advocates of the two systems there has been great rivalry. It may, however, be stated that, with the exception of Germany, the various nations have generally adopted the interrupted-screw system.
    “Among the latter nations is the United States. All the guns that have been built at the national foundry have breech-closing mechanisms of the interrupted-screw systems. This system has been adopted after long and careful criticism of the two methods. The United States in its isolated position has felt that it could wait while the conflict between the two systems was going on, and Congress was loath to appropriate money for the building of heavy guns until the superiority of some one system became evident. It can hardly be said with fairness that such a superiority has become manifest.
    “ It can be said, however, that both systems have proved themselves reliable, serviceable, and durable; each has its advantages over the other, and it becomes merely a matter of choice as to which advantage a nation considers the most desirable. The principal advantage of the Krupp system is its simplicity. It is, on the other hand, obliged to employ a much inferior gas chech. A few grains of sand or slight fouling is sufficient to allow a slight escape of gas, and the erosion once begun will soon destroy the gas check.”
    Engineering has (vol. 49, p. 403 et seg.), in the number for April 4, 1890, an article entitled “ The De Bange system,” from which the following are extracts:
    “ It is very generally assumed to be a fact that French modern practice in the manufacture of ordnance is largely represented by the de Bange system, which forms a specialty of the Cail Company, and the almost universal manner in which some of the most important details of this system have been adopted, attests clearly the value of the services rendered to gun constructors by the able director of the Cail works. Colonel de Bange has been obliged to resign his situation of general director of the Cail works nearly a year ago. In France, England, and the United States more that one special feature of the standard breech-closing mechanism in one form or another is that of de Bange, and its wide adoption is the best evidence of its practical value. *****
    “ The French breech-closing system of interrupted thread, which, with the exception of Krupp, is practically adopted by all gun manufacturers, is accepted as thoroughly trustworthy ; thanks to its simplicity, lightness, and the rapidity with which it can be handled, the efficiency of modern ordnance has been vastly increased, and it was this system that was adopted, after long consideration by our own War Department when, very tardily, we abandoned the crude and clumsy method of muzzle-loading, to which we had clung with so much pertinacity long after it had been given up by other nations. As we have seen in previous articles, this system of breech closing is claimed by France for Treuille de Beaulieu and Yerchere de Reffys. During the war of 1870 France possessed a considerable number of field guns fitted with the interrupted-screw breechblock, while nearly all of the heavy ordnance in the navy was constructed on a similar principle.
    “ Immediately after the termination of the war the first and most pressing care of France was to renew her armament, and it was at this time that Colonel de Bange rendered such signal services to his country. The imperfect method of breech-loading then in use was remodeled by him until it took the present well-known form; the modifications he introduced referring most particularly to the lever for operating the block, the arrangement of the latch, and, above all, the obturator, which was an adaptation of the gas check used in the chassepot rifle., and in which the rubber expanding pad was replaced by a packing of asbestos and suet that was found to make a very efficient gas check and to withstand the effect of high temperatures produced by the powder gases. These and some other improvements in detail converted the interrupted screw-block into a thoroughly efficient breech-closing mechanism. Colonel de Bange, however, was not so fortunate with other details in his system.”
    VIII. On January 31, 1894, the claimant, by its attorneys, addressed a substantially identical communication to the Secretary of War and Secretary of the Navy, stating its claim for the use of its said patented invention, and requesting the payment of just compensation therefor. The letter to the Secretary of War was as follows:
    “ WashingtoN, D. C., January SI, 1891¡..
    
    “ The honorable the Seceetaex of WaR.
    “ Sie : We have the honor to inform you that we have been retained and empowered by the Société Anonyme des Anciens Établissements Cail, of Paris, France, to take proper measures to recover such compensation or royalties as may be justly due to that company for the use of the invention secured to it by letters patent of the United States No. 301220, granted July 1, 1884.
    “ The invention patented to the above-named company under the letters patent aforesaid is an ‘improvement in breech-loading ordnance ’ invented by Charles T. M. V. de Bange, a retired colonel of the French army, the particular improvement in question being well known to the ordnance officers of your department as the ‘ de Bange gas check.’
    “ The device in question performs a function indispensable in modern breech-loading • ordnance — to wit, hermetically closing the breech against the escape of the gases of explosion, while at the same time not interfering with the expeditious withdrawal and insertion of the breechblock or plug.
    “ The de Bange gas check has, after thorough investigation and study of all devices and means designed to accomplish the same object, been approved by the ordnance officers and authorities of this Government. Experiments with and testing of the device was begun the same year the patent was granted, 1884 (see Beport of Chief of Ordnance of the United States Army of that year), and continued for several years thereafter. Full detailed description and drawings of the device in question are found in the report for 1886, and the result of these studies and experiments has been that the great merit and superiority of the de Bange gas check has been acknowledged and the device adopted for all the guns and mortars of 6-inch caliber and upward made by or for this Government.
    “ Touching the value of the invention, we have made careful inquiries and examination; but as it is the desire of our clients to arrange terms with the Government of the United States which will justify and encourage the latter to adopt and use the invention in every piece of ordnance where its employment would be beneficial, and as they have authorized us to accept a royalty which will be at once recognized as a very small compensation for the known value of the device, it will be unnecessary to go into a discussion of this point.
    “ We have been authorized by our clients to grant licenses for the use of their said inventions at a rate of one per cent of the cost of the gun, it being recognized that the importance of the gas check increases with the caliber of the gun and the size of the charge it is designed to sustain.
    “ For the purpose of arriving at a uniform rate and of facilitating the completion of arrangements between the Government and the company to whom its letters patent have been granted, we have deemed it expedient to take a low average price and apply it to guns of all caliber. This uniform rate we would fix at $200 per gun. As the cost of these pieces is from $6,000 to $50,000 each, we think you will perceive at once that the patentee is desirous of making an ar-rangment advantageous to the Government, and which you will have no hesitation in assenting to.
    “ This proposition is submitted for the purpose and with the object of arriving at a speedy settlement, and of course does not represent the measure of value of the invention, which is now recognized in all the leading nations of the world.
    “We presume that, following the usual course in such matters, you will, before finally acting upon this offer, take steps to inform yourself touching the matters herein presented by referring to the officers of the Ordnance Bureau. We beg to be advised of your action in the premises, and in case you should see fit to refer this proposition to a board of officers for report and advice we will take pleasure in appearing before it and answering any questions that may be asked. We would beg to be notified of the time and place in case our presence for such purpose be desired or permitted.
    “ We have the honor to be, with great respect, your obedient servants,
    “ Pollok & Mauro.”
    Claimant’s communication to the Secretary of the Navy was the subject of a report and recommendation by the then Chief of Ordnance, Admiral W. T. Sampson, as follows:
    “ No. 2043.]
    “ Bureau oe OrdNANCe, December A 189J¡..
    
    “ Respectfully returned to the Department.
    “ The gas check applied to guns constructed for the navy is that illustrated in United States letters patent No. 318093, of May 10,1885, and so far as this patent is valid no royalties should be paid. (See Court of Claims Reports, p. 334, vol. 23, 1887-88.) If, however, as the Bureau believes to be the case, the above-mentioned patent is only valid so far as it covers improvements on the de Bange patent (No. 301220, of July 1, 1884), then, so far as the latter patent is valid, the within claim for royalties, in the Bureau’s opinion, is a proper one, and would be maintained by the courts.
    “ It must be noted, however, that until recently there has been no authority of law for the payment of royalties out of the naval appropriations, and the manufacture of most of the gas checks in question had been completed prior to the legislation giving such authority. Moreover, the Bureau is of opinion that the Davis patent (No. 318093, of May 19, 1885) covers real and important improvements, without which it is doubtful if the de Bange system would have been adopted for United States naval guns, and consequently it will be necessary to decide as to the relative values of the device in its original and improved forms. The fact that practically the same gas check is in use in all United States Army guns of recent construction, and is being applied to guns now being made by the Bethlehem Iron Company, under contract with the War Department, should also be considered, since independent action on the part of the Navy Department might easily be against the interests of the Government.
    “ It is therefore recommended that an investigation be made in regard to the de Bange patent, and if this patent is concluded to be valid that the War Department be consulted as to whether a definite sum, to be fixed upon either by a board or in some other way, should not be offered the claimants for the right on the part of the Government to use the device in question on all its guns.
    “ W. T. Sampson,
    
      “ OThief of Bureau of Ordnance.”
    The final action of the Navy Department upon petitioner’s claim was communicated to the petitioner in a letter of the Secretary of the Navy, dated December 31, 1894, as follows:
    “ Navy Department, 'Washington, December SI, 189J¡..
    
    “ Gentlemen : The Department has carefully considered the questions presented in the brief filed by you, as well as in former correspondence, relative to the matter of the claim of the Société Anonyme des Anciens Établissements Cail for compensation for the use by the United States of a gas check invented by Col. Charles T. W. Y. de Bange, of the French army.
    “ It appears that the matter is now in such a condition that it will in all probability involve not only questions arising under the patent issued to Colonel de Bange, but also those growing out of the claims and affecting the rights of other patentees. Under these circumstances the department is of opinion that the full consideration and determination of these questions can be more certainly and equitably reached and the rights of all the parties concerned, as well as the Government, more definitely ascertained and assured through the medium of a court of justice. It is therefore suggested that the necessary proceedings for the consideration and adjustment of the matter by the Court of Claims be instituted.
    “ Very respectfully,
    “ H. A. HERBERT, Secretary.
    
    “ Messrs. Pollok & Mauro,
    
      “Attorneys at Law, Washington, D. (7.”
    
      The final action of the War Department was communicated to claimant’s attorneys in a letter dated January 14, 1895, in which the language and suggestion of the Secretary of the Navy were adopted substantially verbatim:
    
    IX. “ United States Patent Office. — James B. Davis, of Washington, District of Columbia. — Gas check for ordnance.
    “ Specification forming part of Letters Patent No. 318093, dated May 19, 1885.
    “Application filed December 23, 1884. (No model.)
    “ To ail whom it may concern:
    
    “ Be it known that I, James B. Davis, residing at Washington, in the District of Columbia, have invented certain new and useful improvements in gas checks for breech-loading ordnance, of which the following is a specification, reference being had therein to the accompanying drawings.
    “ This invention relates to gas checks for breech-loading ordnance, and it consists in certain improvements, as hereinafter set forth and claimed.
    “ The object of the invention is to produce a gas check which will operate perfectly to close the breech of a breech-loading cannon against gas escape, and which will not “ set ” in expanded position.
    “ Prior to my invention gas checks somewhat similar to mine had been used, but the rings were of soft metal, and it frequently became necessary to pass a rod into the gun from the muzzle in order to start the breech after firing.
    
      “ My invention is particularly intended as an improvement on Patent No. 301220, of July 1, 1884.
    “ In the drawings, figure 1 is a longitudinal section of a portion of the breech plug of a gun with my gas check applied. Fig. 2 is a face view of one of the gas rings. Fig. 3 is a view of the gas check in position in the breech of a gun.
    “A indicates a breech plug, which is usually provided with a mutilated screw thread to secure it in the breech of the gun A2.
    
      “ B is the so-called £ mushroom,’ the head b forming the front of the breech plug. The stem V of the mushroom is screw-threaded, and lock mits C O' on said stem bear against the spring D, which rests against the shoulder a' in the plug, serving to draw the mushroom toward the rear of the plug with a spring pressure.
    “ E E' are steel plates having central holes, e, for the passage of the mushroom stem, and being concaved between the central stem and the outer edges. The edges f f of the plates E E' are brought nearly to knife edges. The periphery of each plate is a cylinder which will just enter its seat in the gun. In the annular space between the plates E E' there is a bag or cushion, K, preferably of canvas, said bag being filled with a slightly compressible fibrous material, as asbestos and tallow. The plates E E' and the packing between them can be removed by unscrewing the nuts and removing the mushroom.
    “ I find it more convenient in manufacture to make the rings E E' separate from the plug and mushroom than to turn them up solid with those parts.
    “ When a gun having this gas check in position is fired, the backward pressure of the powder gas on the mushroom expands the bag and its filling radially, which also expands the knife edges of the rings at / f', making a tight joint.
    “A compound plate of brass and tin or brass and copper has been used in the location of one of my plates E E', but said plate differed from mine in material, in structure, and in function.
    “ I claim—
    “ 1. In combination with the breech plug and mushroom head, a pair of steel rings surrounding the stem of said head, said rings have annular concave spaces in their proximate faces, and a textile bag filled with fibrous material between said plates, substantially as described.
    “ 2. The combination, with the breech plug of a heavy gun, of a mushroom head secured thereto by nuts on the mushroom spindle, a spring pressing the mushroom backward, a pair of steel rings, E E', between the head and plug, and an elastic cushion between the steel rings, all substantially as shown and described.
    “ In testimony whereof I affix my signature m presence of two witnesses.
    “ James B. Davis.
    “ Witnesses:
    “ W. A. BaRtlett.
    “ J. PIarry Stuart.”
    X. “ United States Patent Office. — Gregory Gerdom, of Sandy Hook, New Jersey, Assignor of one-half to John PI. Beynolds, of Troy, New York. Gas check for breech-loading guns.
    
      “ Specification forming part of Letters Patent No. 539733, dated May 21, 1895.
    “ApiDlication filed Marcia 6,. 1S95. Serial No. 540733. (No model.)
    “ To all whom, it may concern:
    
    “ Be it known that I, Gregory Gerdom, a citizen of the United States, residing at Sandy Hook, in the county of Monmouth and State of New Jersey, have invented certain new and useful improvements in gas checks for breech-loading guns; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.
    “ My invention relates to improvements in gas checks for breech-loading guns, and it consists of certain improvements in the type of gas check ordinarily known as the De Bange gas check in which a plastic pad made mostly of asbestos is used.
    “The object of the invention is to produce a gas check which will operate efficiently to close the breech of a breech-loading gun against the escape of the gases formed by the explosive, and which will permit the free and easy movement in and out of the breech plug. Prior to my invention certain gas checks have been used for this purpose in which the plastic pad was contained between two metal disks with their lips on their circumference, which were expanded outward against the bore of the gun due to the compressive action of the powder gas on the plastic pad. These lips being bound to the circular disks were only elastic on their edges and the repeated expansion outward of these lips caused them to take a ‘ set ’ and bind hard against the walls of the gun so that the withdrawal of the breechblock after firing was made with the greatest difficulty. This made the diameter of the lips larger than was designed so that they frequently had to be turned down to the required size. Again, to facilitate the easy withdrawal of the breechblock after firing, the seat on the walls of the gun on which the lips of the metallic disks bear was made conical, the diameter in the rear being larger than the diameter in front. This required that the rear metallic disk be larger in diameter than the front one and that their circumferences should also be made conical. As the limit of expansion of the small lips was very small, the diameter of the disks had to be made very nearly the diameters of the seats for the lips in order that the lips might expand out to the seat to form a close joint. Certain difficulties in manufacture prevented the accomplishment of the proper fit. Again, if the pads varied in thickness, the clearance between the front disk and the walls of the gun also varied and might be sufficient to permit the gas to pass the front disk and penetrate the pad. It was to remedy these and other defects that the hereinafter described improvements were made.
    “ Reference is had to the accompanying drawings, in which the same parts are indicated by the same letters throughout the several views.
    “ Figure 1 represents a central longitudinal section through the powder chamber of a gun, showing the gas check in the position it would assume before the gun is fired. Fig. 2 represents a front view of one of the split rings used in the gas check, and fig. 3 represents a transverse section of the same. Figs. 4 and 5 represent views similar to figs. 2 and 3 of another one of these split rings used on the exterior of the plastic pad; and figs. 6 and 7 represent a similar view of the smaller ring, which is mounted on the spindle of the mushroom head and prevents the exuding of matter from the plastic pad through the center of the breechblock.
    “A represents the body of the gun, which is provided with a powder chamber A', and the ordinary slotted chamber A2 for the interrupted-screw breechblock B. The breechblock is provided with a cylindrical chamber B' for the enlarged portion C' of the stem, to which the mushroom head C is secured. The shank C2 of said stem passes to the rear in the breechblock in the well-known way. This enlarged portion C' of the stem is curved outward as at o', and terminates in a cylindrical shoulder c as shown in fig. 1.
    “An annular plate or washer D fits against the face of the breech plug B2, and fits loosely over the stem C/ and also loosely in the powder chamber A'. This washer D has an annular recess terminated by the shoulder d cut in its front face to receive the split ring F, which has a clearance between it and the said shoulder of about two-hundredths of an inch, and thus allows the said split ring to be sprung inward as the breechblock is forced forward in the powder chamber. The said ring is made somewhat larger than the interior of the powder chamber and has to be sprung into position. The small split ring H incloses the stem and prevents the exuding of the materials of the pad into the chamber B'. Forward of the rings F and H and the washer D is the plastic pad E made of asbestos and tallow, as in the De Bange system of gas checks, and covered with canvas e. Outside of this pad tire ring K is put around the inner face of the mushroom head C. This ring K is made somewhat larger than the interior of the powder chamber and has a clearance of two-hundredths of an inch from the shoulder c, so that the said ring may be sprung inward as the breech plug is forced forward in the powder chamber. These two rings F and K are split as at † and h and are curved as at f and k', respectively, as shown most clearly in figs. 2 and 5.
    “ When the gun is fired the gas, acting on the mushroom head, forces it backward, compressing the plastic pad E and causing it, by means of curve c' of the spindle, to expand radially against the walls of the gun, carrying with it the highly elastic split rings and, together with the rings, forming a gas-tight joint where they bear hard against the seat.
    “ The diameter of the split rings is slightly larger than the diameter of the seat, so that they should always be in contact, but in case they were not, their high capability for expanding circumferentially and also radially, due to their being split, would easily enable them to be expanded for a considerable distance by the plastic pad until they come in contact with their seat.
    “After the discharge of the gun the various parts assume their normal position and allow the breechblock to be opened with the ease with which it was closed before firing.
    “ The rings are highly elastic by reason of their being split, so that they are easily expanded and easily contracted after the pressure which expanded them has been removed. Their being of a larger diameter than their seats, they are always in contact with the said seats, and consequently always protect the edges of the pad, preventing their being destroyed by the gas and also preventing any exudation of the plastic material of which the pad is composed. At the same time being expanded by the great pressure due to the expansion of the plastic material, they form with the pad a gas-tight joint where they are in contact with the walls of the gun. Another important point is that by splitting the rings they will compress as well as expand. It is thus possible to make them, in their natural state, from one one-hundredth to two one-hundredths of an inch larger in diameter than the diameter of the seat, so that when the breechblock is forced into the gun they bear against the walls of the gun for some distance before they reach their seat and scrape off any residue or fouling that may have been left there, leaving a clean smooth surface for them to bear against under pressure, thus better insuring a perfect joint. Again, on account of their being larger in diameter than their seat, and on account of their great expansibility the coning of the gas check seats need not be made to such fine dimensions, thus reducing cost-ón account of the rings being split they are capable of being compressed as well as expanded and consequently they do not bear hard against the walls of the gun after the pressure has been removed, allowing the breechblock to be opened easily. Furthermore, the split rings being of same thickness and being beveled to correspond with the coning of gas chock seat have quite a considerable bearing area on the walls of the gun and consequently do not indent it or score it as a thin lip would do when its thin edge is in contact. The split in the rings with the pad forms a gas check in itself so that no gas can pass through the split and get into the pad. These and the various other advantages of the herein described construction would readily suggest themselves to anyone skilled in the art.
    “ Having thus described my invention, what I claim, and desire to secure by letters patent of the United States, is—
    “ 1. The combination in a gun of a breechblock provided with a recess in the face thereof, a movable head projecting in front of said breechblock and provided with a stem entering said recess, a washer in front of said breechblock and loosely encircling said stem, a small split ring around said stem in front of said washer and closely engaging said stem, a plastic pad included between said washer and said movable head, and two resilient split rings, made of greater diameter than the powder chamber and mounted one at either side of the outer edge of said pad, substantially as and for the purposes described.
    “ 2. The combination in a gun of a breechblock provided with a recess in the face thereof, a movable mushroom head C curved on its rear face as at o', and shouldered as at c, and having a stem projecting into said recess of the breechblock, a washer in front of said breechblock and loosely encircling-said stem, a small split ring around said stem in front of said washer and closely engaging said stem, a plastic pad included between said washer and said movable head, a resilient split ring K curved as at ¥ made of greater diameter than the powder chamber and mounted exterior to said shoulder c and forward of said pad, and a ring curved as at f mounted in front of said washer and in rear of said pad, substantially as and for the purposes described.
    “ 3. The combination in a gun of a breechblock provided with a recess in the face thereof, a movable mushroom head C curved on its rear face as at <?', and shouldered as at c, and having a stem projecting into said recess of the breechblock, a washer in front of said breechblock and loosely encircling said stem and shouldered as at d, a small split ring around said stem in front of said washer and closely engaging said stem, a plastic pad included between said washer and said movable head, a resilient split ring K curved as at ¥ made of greater diameter than the powder chamber and mounted exterior to said shoulder o and forward of said pad, and a resilient ring F' split as at / and curved as at f, made of greater diameter than the powder chamber and mounted exterior to said shoulder d and in rear of said pad, substantially as and for the purposes described.
    “ In testimony whereof I affix my signature in presence of two witnesses.
    “ Geegoey Gerdom.
    “ Witnesses:
    “ Carl F. Jeansen.
    “ Gregory Gerdom, Jr.”
    The De Bange obturator, as described in claimant’s patent and specified in claim 1 thereof, has been used by the Government of the United States between July 1, 1884, and July 1, 1901 (the term of said patent), in breech-loading guns, as follows:
    In guns made for the navy:
    4-inch_ 4
    5-inch_ 2
    6-inch_133
    8-inch_ 81
    10-inch_ 25
    12-inch_ 16
    13-inch_ 34
    - 295
    In guns made for the army:
    3-inch .2 rifles-362
    3-inch .6 rifles- 25
    5-ineh siege rifles- 44
    7-inch siege mortars- 61
    7-inch siege howitzers- 41
    8-ineh rifles- 94
    10-inch rifles-127
    12-ineh rifles- 115
    12-inch mortars-354
    - 1,223
    Total-„-1,518
    
      Mr. Philip Mauro for the claimant. Mr. Timothy D. Mer-win was on the brief.
    
      Mr. Malcolm A. Coles (with whom was Mr. Assistant Attorney-General Van Orsdel) for the defendants. Mr. Charles C. Binney was on the brief.
   Booth, J.,

delivered the opinion of the court:

This is a suit for the recovery of royalties alleged to be due the claimant because of the use by the defendants of a certain patented invention, the patent in issue being a gas check or obturator, a device indispensable to the effective operation of breech-loading cannon. Defendant concedes the use of such a mechanism, but disclaims the use of claimant’s device by attacking the scope of the patent.

A defense going to the jurisdiction of the court is raised. We think the question is settled by the case of United States v. Berdan Fire Arms Co. (156 U. S., 552). The findings disclose an invitation to present the details of the patent to the defendant, its examination by a board of officers appointed to investigate such inventions, and its final use without the •slightest claim of ownership. Nothing appears to show an intention to dispute claimant’s title to the patent, hence an implied contract arose to pay for such use.

The material issue involved is the precise limit or scope of claimant’s patent as appears from specifications and claim 1 of his letters No. 301220.

From a careful examination of the language of the claim and specifications of the patent in suit, it is obvious that the same is susceptible of two constructions. This is likewise apparent from the history of the patent in the Patent Office, from which it appears numerous amendments were required of the claim before final allowance was granted. Claimant’s contention is predicated upon such a construction of claim 1 as limits the real patent to a “ yielding packing ring of asbestos and tallow,” defendants asserting that the language of the claim expressly describes the patent of a device composed not only of a yielding packing ring of asbestos and tallow, but also includes the employment of the other elements described in the claim, which constitute an integral part thereof and are inseparable therefrom.

The state of the art at the time of the granting of patent No. 301220 clearly indicates the novelty of the De Bange patent. Many breech-loading devices as applied to firearms had been previously patented, several of which had been more or less satisfactory, and used considerably. It is indisputable, however, that until the advent of the De Bange patent the development of the art had brought forth but two breech-loading mechanisms universally recognized and employed by the nations of the world in the use of their offensive armament, viz, the Krupp or sliding-wedge system and the interrupted screw or French system. The De Bange patent was applied wholly and exclusively to the interrupted screw of French system of fermeture. The obstacle, which had in each instance forestalled the successful and effective operation of each breech-loading mechanism preceding the De Bange patent, had been the failure to discover an effective system of obturation. In the discharge of a projectile from large cannon there is instantaneously generated a large quantity of poisonous gases, which, under the tremendous pressure of 35,000 pounds to the square inch, seek instant escape toward the rear as well as the muzzle of the gun. If permitted to come in contact with the breech-loading mechanism attached to the rear of the gun, they engender a system of erosion fatal to the life of the mechanism itself. For many years the inventive genius of those skilled in the use and science of firearms concerned themselves in an effort to discover some device, some process, by which the escape of gases generated by the explosion of the projectile could be checked in their efforts to escape to the rear of the gun. To accomplish the result, some element or combination of elements must possess the inherent qualities of being capable of instantly receiving laterally the tremendous pressure of the gases, expanding with equal alertness axially, so as to close effectually the joints of the breech-loading mechanism, and then speedily resume its normal shape, so as not to retard the reloading of the cannon.

In January, 1867, Antoine Alphonse Chassepot, of Paris, France, invented and patented an obturating device, which when applied to small firearms was an eminent success, but proved a failure in its application to field guns and cannon of large caliber. The functioning element of the Chassepot obturator was a “ cylindrical disk or tube of vulcanized india rubber.” In 1868 Colonel dry attempted obturation by cups of pasteboard inserted so as to cover the head of the cartridge. His invention effected obturation, but encountered such difficulty in extracting the device from the cannon after the discharge that it was abandoned. The Elswick cup and the Broadwell ring checks had been in successful use in connection with the slotted screw breech plug, but- not-as to the interrupted-screw system of fermeture. In 1872 Captain de Bange, an officer of the French army, began a series of experiments looking toward the perfection, among other things, of an obturating device. Soap, molded leather, a mixture of talc and tallow and soap with a base of lime were successively tried to supply the indispensable element of yielding packing obturator, but all to no avail. Finally, and as a result of his experiments, he combined a mixture of asbestos and tallow, formulated it under great pressure in the shape of a ring, and applied it to the interrupted screw or French system of fermeture, as set forth in his patent. It is therefore almost inconceivable how the court can, in view of the state of the art priorto the De Bange patent, arrive at any other conclusion than that the De Bange invention was, in fact and in substance, a discovery of a distinct, new, and novel system of obturation. -No system of obturation prior to it had anticipated the use of a yielding packing ring of asbestos and tallow; repeated attempts at a substitute had failed, and the findings disclose its successful use and operation ever since. Was this invention patented by letters patent No. 301220?

The language of the specification in its introductory part says: “ I have devised a system of packing placed in advance of the plug, and which is expanded by the force of the explosion of the powder to make a tight joint to prevent the ^leakage of gas;” then follows in detail the construction and operation of the device. Claim 1 is drawn with the same preciseness, and, in conjunction with the claim 3, covers in toto the details of the patent. The specifications and claim being addressed to those skilled in this particular art or science, only such precision and nicety was required as to enable such a class of persons to use the invention. (Loom Co. v. Higgins, 105 U. S., 580.) It is difficult to perceive how one skilled in the particular art or science of breech-loading ordnance could fail to instantly avail himself of the essential, the functioning, the indispensable element of the device described in the specifications and claim, to wit, “ the ring of asbestos and tallow.” Every description of the patent in either the specifications or claim imports in terms the predomination of the one central idea of a yielding packing composed of asbestos and tallow. It is the invention; without its presence the device fails, with it the device succeeds. The details of construction are of minor importance. Shall De Bange be denied the character of inventor because, subsequent to his patent, the yielding ring of asbestos and tallow is incased in canvas instead of copper; because split steel rings instead of brass are forced by the expansive quality of the pad to perform exactly the same functions? Much expert testimony has been adduced to aid the court in the construction of this patent. It is of the usual contradictory character and wholy irreconcilable; but throughout it all it nowhere appears that any device subsequent to the De Bange patent has ever been used by the defendant that did not appropriate and embody the use of a ring of asbestos and tallow. The court is of the opinion that the invention described -by the language of the claim was the yielding pad of asbestos and tallow. The nonessential details of construction found in the specifications and claim for a patent should not be allowed to obscure the real invention, if it can be validated, without doing violence to the languge thereof. In Whipple v. Middlesex Co. (Fish Pat. case) the court said:

If by examination of the specifications, and applying to it the then state of the art, we can learn what the invention was, then the claim, which was designed to be a condensed summary of the invention, is to be construed so as to be coextensive with the invention, if that can be done without doing violence to the language.

In Consolidated Fastener Co. v. Columbia Co. (79 Fed. R., 795) the court said:

That the patent is susceptible of the latter construction must be admitted. Many plausible reasons can be advanced to sustain such a construction. On the other hand, an equally cogent argument can be advanced in favor of the former construction. Confining the discussion to the language of the patent, it is manifest that where two interpretations are possible, that one should be chosen which upholds the patent. If the defendant’s contention be upheld, the patent ceases to be protection. The essential feature is strangled by a useless and nonessential feature.

A multiplicity of cases too numerous for citation, extending over tbe entire subject of construction of patents, have placed the courts in the attitude of extending to inventors the protection of the patent laws of the. country when the real invention is capable of ascertainment and it distinctly appears from the letters patent that the inventor has contributed to the art a useful and valuable invention. The rule of ut res magis raleat quam pereat is almost universally applied rather than deprive an inventor of the fruits of his industry by technical construction. (McCormick v. Talcott et al., 20 How., 402; Turrill v. Railroad Co., 1 Wall., 491; Corning v. Burden, 15 How., 268; Van Master v. Miller, 15 Blatch., 562; Winans v. Denmead, 15 How., 330.)

It is urged with much persistency that the rejection of the claim as first specified, by the Patent Office, precludes a claim for a patent covering a distinct species of packing. It is to be observed in this connection that the claimant did not introduce into his amended claim any new element or eliminate any old one.

Claim 1, the only claim in issue in this proceeding, remained substantially the same. It is not pretended that the language thereof as first specified or subsequently amended was materially changed. There was absolutely no proviso or limitation as applied to the yielding packing engrafted into this claim at any stage of the proceedings. The yielding packing was designated by the letter “ M ” in claim 1 when originally presented to the Patent Office. This description of the real invention continued to be employed throughout the entire proceedings, and finding 1 discloses that it is now the same. To hold otherwise, claim 3, a detail of construction, containing nonessential elements, must be read into claim 1. Both claim 1 and claim 3 construed together indicate an identity of invention, claim 1 being a specification of the real patent and claim 3 a specification of construction and utilization. If such narrow limitations can be imposed upon claim 1 of the De Bange patent as to restrict the patent to a yielding pad of asbestos and tallow, almost totally enveloped in the elastic shells of copper and placed between rigid shells of brass, serving as specified therein, then subsequent inventors can with impunity appropriate the essential element of any device, universally recognized as elfective and useful, a distinct and important advance in the art, the indispensable and functioning feature of all its successors, it being conceded in the defendant’s brief that Captain de Bange was the first to use a ring of asbestos and tallow.

Patent No. 318098 of James B. Davis is expressly stated to be an improvement on patent No. 301220 (the De Bange patent). The improvement consisted of the introduction of steel plates, the edges of the same being brought nearly to the thinness of a knife edge. The pad of asbestos and tallow is retained, although incased in canvas. The device was not a pronounced success and its use not employed. May 21, 1895, letters patent No. 539733 were issued to Gregory Gerdom covering an improvement, as stated in the specifications, “ to the type of gas check ordinarily known, as the De Bange gas check, in which a plastic pad made mostly of asbestos is used.” The differentiating feature of the Gerdom patent was the use of a split steel ring slightly larger than the inner circumference of the cannon instead of the brass ring specified in claim 3 of the De Bange patent. The pad of asbestos and tallow was employed by Gerdom, and, with the exception of the split steel ring, substantially as specified by De Bange.

The specifications for the Gerdom patent disclose a device the operation of which depends upon the expansion of the pad of asbestos and tallow. “ When the gun is fired the gas acting on the mushroom head forces it backward, compressing the plastic pad E and causing it, by means of curve C of the spindle, to expand radially against the walls of the gun, carrying with it the highly elastic split rings forming a gas-tight joint where they bear hard against the seat.” (Finding IX.) The detail description of the De Bange patent forwarded by Lieutenant Chadwick in his letter of April 27,1883 (Finding III), specifies a canvas covering for the pad of asbestos and tallow, and likewise shows the employment of split rings. The detail of construction as found in this letter and the specifications of the Gerdom patent are strikingly similar, save in the substitution of steel for brass. De Bange treated the detail of construction as nonessential. The record discloses that in all subsequent inventions the pad of asbestos and tallow is the functioning element of the device, without which its utility is as nothing. The necessary expansion, indispensable to forward the operation of both the Davis and Gerdom patents, is supplied by the De Bange pad of asbestos and tallow. The defendants used the Gerdom improvement and paid the patentee substantial royalties therefor. That it was an improvement of value is not disputed ; but it was only an improvement, and did not supplant the De Bange patent as specified and claimed for in letters 301220.

There is no testimony in the record upon which the quantum of damages can be predicated. The measure of damages would be the value of the device to the defendants. Following the precedents heretofore established, the case will stand upon the docket, with leave to furnish testimony upon this point.  