A Method of Registering the Rotation of a Shot by Photography
By F. Neesen, Professor in the United Artillery and Engineers' School at Berlin
[Translated from the Archiv fur die Artillerie- und Ingenieur-Offiziere des deutschen Reichsheeres, January-February, 1889.]
The possibility of estimating the rotation of a shot by means of photography was suggested by Captain A. D. Dregar several years ago. His idea was to place a sensitized plate inside the projectile, but he never carried out the plan experimentally. I have endeavored to prove the practicability of the scheme by means of a model, and for this purpose had constructed an apparatus, the principle of which may be thus described :
Upon a sensitized plate a (Fig. I) a photograph of the narrow opening b is made by the ray of light passing through it. Inclining the plate changes, of course, the position of the photograph upon it. Through the advice and assistance of Prof. H. W. Vogel I became convinced that if a photographic chamber, completely closed except a small opening i mm. in diameter, were given a quick to and fro motion, a sharp trace of the ray of light x would be received upon the plate a. I accordingly arranged an apparatus in the following manner:
A (Fig. 2) is a short metallic cylinder having a screw -thread cut upon it outside, on which is a revolving ring B. Two short arms cc are fastened to A and put in a ring of the Bohneuberger apparatus. The sensitized plate is placed in the chamber K, which is screwed into A. A cover d closes the chamber K, and at the same time holds securely the plate a, which moves upon a plate-spring. In d is the opening b 34 mm. in diameter; a cap It closes this Opening. A carries further the sliding-pin C, over which is slipped a second metallic cylinder A and a chamber K, similar to K. Besides the cap R, a slide valve n (Fig. 3) is used to close the opening b. The valve is thrown out by centrifugal force during the revolution of the cylinder A. A cord is wound upon s, the rapid drawing off of which imparts rotating motion to the cylinder A with the chamber K,; a spring may be used instead of the cord. By the revolution of the ring B the center of gravity of the apparatus is displaced and a photograph obtained of the oscillations of the axis of rotation. In this manner the sketches in Figs. 4, 5, and 9 were obtained, which need no explanation.
EMPLOYMENT OF THE SHOT.
I. Rotating Plate.
If it is desired to obtain the picture of the oscillation of a rotating shot, the arrangement is very simple. The point of the shot must be capable of being unscrewed and the sensitized plate placed inside. The plate is of metal, upon which the negative paper is secured, or it is coated directly with bromide of silver ; a small hole b is cut through the nose of the shot, which is uncovered automatically, as already explained, by the flying out of the slide valve n.
II. The Stationary Plate.
In order to obtain the track of light on a non-rotating plate, the following arrangement can be made (Fig. 8):
The sensitized plate (a) is secured with a pin in a hollow bed f, care being taken that it does not touch!. It is held in suspension by two small wires II. In order to prevent any disturbance of the plate by the shock of discharge, a ring c is used, on the inner half of which the plate a is placed. Cis enclosed in a cylindrical room filled with a fluid, which also fills the hollow chamber! and the space between a and d, so that the shock is dissipated by the liquid and all strains upon the plate divided. As a bears upon the shot only on the small pin f, it remains steady during the rotation of the projectile.
The plate is kept from flying back upon its seat at the instant of discharge by ribs cast on the inside of the ring c. The tendency of the plate to rotate with the shot is further diminished by the fact that its center of gravity is thrown as far as possible out of the axis of revolution.
From the curve Oo (Fig. 6) which is made upon the plate, and from the co-ordinates Od and Oe of this curve, entire deviations of the axis of revolution are obtained for every angle of a corresponding to ?.
A. G.
QUADRANT ELEVATION FOR NAVAL ORDNANCE.
BY CAPTAIN P. J. R. CRAMPTON, R. A.
The improvement in shooting which has followed the use of the clinometer instead of the tangent scale, in laying guns for range, is most remarkable. The cause of the improvement is chiefly to be found in the fact that with a clinometer a gun, or even a number of guns, may be laid, mechanically so to speak, for exactly the same range, instead of depending on the uncertain skill of a variety of individuals, thus eliminating all chance of inaccuracy due to the personal error on the part of the Nos. 1.
This improvement becomes particularly apparent when verifying or picking up ranges by means of trial shots. For comparison let us take the case when verifying a range (1) with, and (2) without the use of a clinometer. In the first case the following method will probably be adopted. The leeward gun will be fired at an estimated range; say, this round apparently falls just over the object fired at. The next gun would be fired with the same elevation; say, this round falls short. Theoretically speaking, the elevation and consequently the range are correct, but it would not be safe to accept it as such without firing another round or two, or a salvo of two or three guns, to test the accuracy of the two first rounds, which would be a waste of both time and ammunition. Take now the case when a clinometer is used to give the elevation, and say that similar results have been obtained in the first two rounds, one round over and the next short, both guns having been laid by the same quadrant elevation. The results of these two rounds would be quite sufficient to determine the range, as any cause of inaccuracy must now be looked for inside the gun. The advantage of being able to lay guns from behind cover, or at night, or on an invisible target, by means of the clinometer, is of course well known.
An extension of this principle to the naval service would be most desirable, as it is evidently adapted for use in connection with the "Director" system at present in the service, and many additional causes of error which are now inseparable from naval gunnery would be removed thereby; but to be successfully applied some modifications are necessary. A spirit clinometer, owing to the motion of the ship, would be useless, and consequently quadrant arcs would have to be used instead. The index plates at present in the service are certainly not so accurate as a clinometer, but no doubt they might very easily be improved by lengthening the radius. The exact moment the ship is on a level keel, or rather the moment when the line formed on the plane of the racers by the intersection of the plane of departure is in the horizontal plane, must also be determined. This moment once determined, the guns must be fired instantaneously, as the ship will be moving with more or less angular velocity. This instantaneous firing is necessary in any case, whether the gun is laid by tangent sight or quadrant, and here the errors inherent to the use of the tangent sight on land are vastly increased. Personal error is bad enough when the gun platform is steady; in this case it is constantly moving, and the No. I has to keep his eye on the target, the trunnion sight, and the notch of the tangent sight at the same time. It is sufficiently hard to focus these three objects when they are all in the same straight line; when one of them is at a distance from this line and constantly moving, the difficulty is greatly increased. Not only has the No. 1 to determine by the eye the moment the sights are aligned with the object, but he has also to fire the gun instantaneously, otherwise commencing to pull the lanyard before the object comes into line ; even when guns are fired by electricity it is impossible to make the hand obey the eye instantaneously. For these reasons it is desirable that the gun should be fired automatically, and electricity lends itself admirably to this purpose.
The difficulty at present is to get an instrument which will show, under the various movements made by a ship at sea, the absolute horizontal, and which at the same time will not be put out of adjustment by the shocks of discharge of the armament. Various plans have been adopted to obtain a reliable ship's pendulum or clinometer, which may be divided into two main classes—those of the nature of a pendulum, and those like gyroscopes. Now a well suspended gyroscope, such as that made by Professor Piazzi Smith, gives excellent results so long as there is a horizontal plane to start from, the difficulty being to start the gyrating disk in the true horizontal plane when the ship is already rolling, which difficulty I believe no one has as yet got over, and even if it were surmounted, the first discharge of a heavy gun would put it wrong. The same objection applies to pendulums and instruments such as that constructed by Mr. Froude, in which the discharge of a heavy gun would almost to a certainty put the long pendulum out of adjustment. This would not necessarily vitiate the graphical record so ingeniously obtained with this instrument, as any inaccuracies in their swing, caused by shocks to the ship or from acceleration, are at once observable on the tracing, and can be ignored when the results are being tabulated, but this would not be applicable to the firing of a heavy gun.
The instrument about to be described is not of so ambitious a nature as Mr. Froude's, which records the angular displacements of the ship and its inclination to the wave slope during the whole of its roll, but merely a clinometer which will show the true horizontal through a space of about I° on either side of the ship's normal position in calm water. This limiting of the scope of record is necessary in order to steady the so-called pendulum between each roll, for the fact has been established that if a pendulum of long period in comparison with that of the ship be suspended at the center of gravity of the vessel, it will remain vertical if steadied at the end of each roll, and so extinguish any moment it may have previously acquired during the preceding roll; whilst a pendulum of comparatively short period will tend to remain normal to the wave slope, if the ship rolls with the waves. Now all clinometers are pendulums in disguise, and generally pendulums of a very short period ; they would, therefore, when the period of the ship coincides with that of the waves, tend to lie in a normal to the wave slope ; but as ships do not as a rule roll into the waves, and as the latter are at all times of uncertain shape and size, a short pendulum will acquire a variety of moments due to the uncertain movements of the ship. But should the pendulum be bound, so to speak, during say nine-tenths of its course, there will not be time for any force except that of gravity to act, and it will show the true vertical. It may be said, should the ship only roll through one degree or less on each side of the vertical, the principle will not apply. This is true; but a modern ironclad rolling takes about to seconds to complete each roll. The motion therefore is so slow that no accelerating or other force is set up and the instrument is still true. What is meant will easily be seen by reference to the section. The instrument is supposed to be centered in a plane parallel to the plane in which the guns are traversed, and is capable of being traversed in the same manner as a gun on a central pivot. When required for use, it is put into a position in which a vertical plane drawn through the centers of the two electro-contacts e e will be parallel to the plane of departure of the gun. It is also supposed to be as nearly as possible at the center of gravity of the ship.
The vessel k is an iron box with a double trough at the bottom (vide figure), with three recesses y into which two tubes k' and one tube p dip. These tubes are hermetically screwed into the top of k. To fill the vessel, petroleum or some other non-conducting liquid is poured in through the filling hole until filled. A small quantity of mercury is then poured down until it rises as high in the trough as shown in the sketch. In doing this it will displace an equal bulk of the petroleum. The filling hole is then closed by the screw plug, whilst more mercury is poured down through the tube p ; as the petroleum cannot now be displaced, the filling hole being plugged and the bottoms of the tubes k' and p being below the surface of the mercury, the latter will rise in the tubes k'. Sufficient is poured in to bring the level up to about the height shown. This level can be exactly regulated by means of the piston and screw shaft in continuation of the tube.
On the vessel k being tilted by the motion of the ship, the mercury will run down to one end and fill up one of the recesses x x. The level of the top of the column of mercury in the tubes k' k' altering with the change of level of the mercury in the troughs until a point w is reached, at which the line of the top of the mercury continually cuts the same point in the center of k'. This is arranged by the shape of the recesses x x, and consequently no further amount of roll will alter the level of the top of the columns of mercury. This will take place after a roll to either side of about to. The level of the columns will then remain the same until the mercury is poured from one recess to the other by the return roll, when the true horizontal will again be maintained for about 10 on either side of the vertical.
The section in the figure represents the level of the mercury at rest; after the instrument has been tilted t° out of the horizontal ; b is the bottom of the trough; vvvv are screens to increase the inertia of the petroleum.
The conditions already laid down are fulfilled by this arrangement. The pendulum is steadied between each roll, and the period during which forces other than gravity can act upon it is very short. At any rate it will start fair after each roll, and the quantity of mercury being small, the moment of inertia is reduced as far as possible, it also will be destroyed between each roll. The shape of the bottom of the trough is a very flat cycloidal curve, except at the ends, where it is steeper ; this is to prevent waves being formed on the surface of the mercury. The inner surface of the vessel k is copper-plated, so that the mercury when touching it will amalgamate on the surface and so prevent friction.
The clinometer is arranged to complete a voltaic circuit, and so fire the guns automatically when the ship is in its normal position, as follows:
The tops of the tubes k' k' terminate in glass tubes w w which are of the same bore as k' k', and into which tubes two steel rods e e project. The depth to which they project is regulated by means of micrometer screws worked by pulleys as shown in the drawing, and the two pulleys are connected by a crossed gut band, so that by depressing one rod the other is raised an equal amount, and vice versa. The rods being fixed so that their lower ends are in a plane parallel to the plane of the gun racers, and the ship being on a level keel, the screw piston shaft is screwed up or down, and the mercury in the tubes so adjusted as just to touch the ends of the rods e e (which are isolated from the rest of the instrument, the latter itself being isolated from its support). If now the rods are connected to opposite poles of a voltaic battery by wires, the circuit will be complete and the current pass; but if the ship rolls the least out of the vertical position, the mercury in one tube will sink and rise in the other end, the circuit will then be cut, as the petroleum which lies on the top of the columns of mercury is a non-conductor.
If now a low tension tube (such as one of the electro vent-sealing tubes now in the service) be connected in series with the circuit, it will explode when the ship is vertical. If more than one gun is to be fired, it will be better to con nect the tubes which are to fire them in parallel with a central station, the poles of this station to be connected in series with the clinometer circuit. A firing key and a switch which cuts out the clinometer circuit, are also placed in the circuit.
Any small errors in range which may be due to the angular velocity of the ship when rolling, or even to incorrect estimation of range, can be corrected by means of the pulleys and micrometer screws, which can, if necessary, be worked by an electric clock from the conning tower. When the switch handle is turned on to the direct circuit, the guns in the battery will be fired as soon as the firing key is pressed down. When the handle is turned to the clinometer circuit and the firing key pressed, the guns will fire as soon as their racers are in the horizontal plane; at any moment, by taking the finger off the firing key the circuit can be cut. Other safety arrangements can be applied to the guns themselves.
THE BASIC DUPLEX PROCESS.
In the Bulletin of the American Iron and Steel Association for July 3d, Mr. Jacob Reese gives the following description of his latest process for the manufacture of steel:
The basic duplex process consists in blowing molten metal with an air-blast while held in an acid-lined converter until the silicon is eliminated and the carbon is reduced to about one-half of one per cent, then transferring the desiliconized metal (minus the slag) into a_basic-lined open hearth, and there boiling out the carbon and dephosphorizing the metal in the presence of a basic slag. This process will work metal of any and every quality. If the metal is high in silicon, the silicon is removed in the acid-lined vessel and the phosphorus and carbon in the basic-lined vessel, so that the silicic acid or dirt formed in the elimination of silicon will not be present in the dephosphorizing period, and a purer metal will be made than by either the basic Bessemer or the basic open-hearth process. The time required to make a heat by the basic duplex process is from three to four hours, the expense of converting being about a dollar a ton less than by the basic open-hearth and a dollar a ton more than by the basic converter.
This process may be practiced to advantage at Pittsburgh, Harrisburg, and in Eastern Pennsylvania; at Richmond, Lynchburg, Low Moor, Milnes, Roanoke, and Pulaski, in Virginia; from Knoxville to South Pittsburg, in Tennessee; and at all points where pig iron can be made to advantage in Alabama and Georgia. It is especially adapted to make steel from the pig iron made at Bessemer, Birmingham, and Sheffield, Alabama.
THE NEW COLT CARTRIDGE PACK,
FOR LOADING ALL CHAMBERS OF A REVOLVER SIMULTANEOUSLY.
The records of the Patent Office show that ever since revolvers came into general use by Colonel Colt's inventions, efforts have been made to devise some means by which the chambers in the cylinder of a revolver could be loaded and reloaded without necessitating the tedious operation of introducing each separate charge singly into the corresponding chamber of the cylinder. This was especially desirable when, before the introduction of fixed ammuni tion, the powder charges had to be each separately measured and poured into each chamber, after which a bullet had to be rammed in front of every charge, and a percussion cap set upon the cone of each chamber. These operations required, of course, considerable time and deliberateness, and were quite out of question when, in the excitement of a fight at close quarters, the revolver came into play. The patents of that period show a number of pouches for carrying the separate powder charges and bullets, with means for facilitating the loading, and also some devices by which the cylinder itself, after being emptied, could be replaced by others, carried for this purpose in loaded condition in a convenient pocket or belt. The first step in the right direction was the introduction of packages containing as many cartridges as the cylinder had chambers, and each cartridge consisting of a powder charge and a bullet wrapped in an envelope of inflammable paper. Then finally the fixed ammunition was invented, where powder, bullet and primer are all held by the metallic cartridge shell. These metallic cartridges are a very great advance from the loose ammunition and from the paper envelope cartridges, and their use requires much less time and care than the latter, even in those revolvers where the cylinder is not removable for ejection of the shells and for reloading, and in using which, therefore, after each shell has been separately ejected, each chamber must be in the same manner reloaded.
The present time, however, has seen the introduction into more general use of revolvers which are constructed for the utmost rapidity of fire, and for this reason are provided with self-cocking locks and with simultaneous ejection. The newest (and best) of this class is the Colt's new 38-caliber revolver, adopted by the U. S. Navy Department; this pistol, while retaining the solid frame of all modern Colt revolvers, allows the cylinder to swing out of the frame laterally, and in this position all the emptied cartridge shells are simultaneously ejected by means of a very simple, but strong and efficient, ejecting device, and the chambers are presented for reloading.
With these facilities for rapid firing and simultaneous ejection, it could not fail that sonic better means for reloading would again be called for, because in cases where, after emptying the chambers, it should become necessary to reload so as to be able to continue the firing, the loading of each chamber singly with cartridges carried in a belt or pouch would require more time than the firing of all cartridges in the cylinder and the ejection of the shells would require collectively ; so that the rapidity of a sustained revolver firing depends mainly on the facilities for reloading. It is therefore apparent that under circumstances where a second or third charge of the revolver may become decisive, that an enormous advantage would rest with that side who could reload most rapidly and thus continue its fire.
These considerations led to urgent calls for reloading devices, from officers both of the navy and of the army ; and General J. C. Kelton, the present Adjutant-General of the U. S. Army, realizing their necessity, wrote in an article entitled "Devices by means of which effective mounted firing with the pistol and carbine can be obtained, by cavalry in attack," published in the Journal of the U. S. Cavalry Association, of March, 1888, as follows : "Such a pack for certain and rapid reloading is absolutely necessary in war, and especially where the pistol is used in hand-to-hand combat, where success depends upon the rapidity with which it can be reloaded and discharged." The same distinguished officer also invented and patented several cartridge packs for reloading revolvers.
Closely following these appeared the Colt cartridge pack, which is an improvement on all prior ones, as it consists of fewer parts and requires much less expertness in its use. This pack was patented in the United States on April 30th, 1889, and its merits are so evident that it was at once adopted and a large number ordered by the U. S. Navy Department for use with the new Colt navy revolver.
The accompanying cuts show the pack and the mode of using it; one of the lower figures on the left represents the entire pack, holding six cartridges, and those on the right show separately the two parts, the ring and the plug, which with the cartridges constitute the pack. The large central figure shows the pack in use for reloading a revolver; the left hand of the operator holds the 38 Colt revolver with its cylinder swung out, presenting all the chambers, while his right hand applies the cartridge pack, by grasping the ring and pushing it towards the cylinder, thus forcing the cartridges into the chambers, while the plug is allowed freely to escape rearward. The outside figure on the left represents an auxiliary implement, the charging block, which serves to assist in assembling the packs before they are served out to the sailors or soldiers. While the assembling can be done without the block, it is done much easier and quicker with it ; this is effected by simply depositing the six cartridges with their bullets in the corresponding six holes in the block, then placing the ring over the heads of the cartridges, and introducing the plug from the top through the central opening in the ring, between the cartridges, and firmly pressing it home until its top flange rests near or on the heads of the cartridges, when the complete pack may be removed from the charging block. The cartridge heads are each firmly held by a shoulder under the flange of the plug, and pressed outward into the corresponding recess in the ring below its flange ; and while the tapering sides of the ring confine the cartridges at the proper angle, the lower part of the body of the plug wedges the cartridges outward at the end of the cartridge shells, without touching the bullets, thus avoiding any disfiguring of these. The bullets, as also the tapering end of the plug, are thus held in the proper position to correspond with the chambers and the central hole in the rear face of the cylinder. As long as the plug remains in the described position between the cartridges, the pack holds firmly together and will withstand quite rough handling without starting apart. When the pack is placed against the rear of the cylinder, each bullet readily finds its chamber, and the end of the plug enters the central recess. On pressing now against the ring, without touching the plug, the cartridges enter gradually into the chambers, and the plug, resting with its point against the bottom of the recess, protrudes rearward from the ring ; when sufficient of this motion has freed the cartridge heads from the shoulder under the flange of the plug, the cartridges are no longer held at an angle, but become parallel to the axis of the cylinder, as the smaller diameter of the plug body, below the shoulder, allows the cartridge heads to move inward and escape from the recesses in the ring ; under the continued pressure against the ring, the cartridges fully enter into the chambers, while the plug drops out at the rear, and the empty ring may be removed.
Thus one single movement suffices to load all six chambers, and this can be done, in fact, even more quickly than a single cartridge can be loaded into its chamber; as it is much easier to remove the pack from its seat in the pouch and use it as above described, than to pick the comparatively small single cartridge from a pouch or belt and guide it to and introduce it into the chamber. Particularly is this the case at night time, for while after a very little practice it is easy to use the pack with the pistol in the dark, the same is quite difficult when single cartridges have to be used.
It has thus been shown that the rapidity of revolver firing really depends on the speed of the reloading, and with the Colt cartridge pack the interval necessary for reloading is so slight that the revolver becomes equal in the rapidity of its fire to a magazine arm with a large number of cartridges in the magazine; the reloading pack stands in fact to the pistol in the same relation as a detachable magazine to a rifle. A revolver provided with an ejector can only attain its best results when accompanied by a reloading pack ; for the advantage of the simultaneous ejection of the shells is of small value if not followed by an equally certain and rapid reloading. The new pouches for the U. S. Navy are arranged to hold several of the packs ready for instant use, the charged packs being served out to the men instead of loose cartridges, and one charging block accompanies every 100 packs.
For cavalry use this pack is excellent, for the trooper can readily use his right hand to load with the pack, while holding the open pistol in his left or bridle hand.
The rings of the pack, being struck up of brass, may be refilled any number of times, as they do not suffer any change from being used ; the plugs, being wood, may be used repeatedly, though long continued use will finally reduce their diameter at the points where the cartridges bear against them, enough to make their replacement by new plugs necessary. However, while at drill, rings and plugs may be saved for recharging; their price is so small that their loss in action will be no more expensive than that of the cartridge shells.
As pistol shooting has of late become very popular, those who practice it with ejecting revolvers may save themselves much useless trouble by supplying themselves with and using these reloading packs. They may be safely carried charged in a pocket, or with the block they can be charged at any convenient time. A lower part may be added which covers the bullets and cartridges and slides on to the ring from below, thus forming a perfect box around the cartridges ; but this is not essential, and is not done in military use. While the pack shown only fits the six-shot Colt 38 revolver, other ejecting revolvers, which present the rear face of the cylinder when open for the use of the pack, can be reloaded in the same manner ; and the packs can be made for any number of cartridges, corresponding to that of the chambers in the cylinder of the pistol.
ON THE RELATION OF THE YARD TO THE METER.
Bulletin No. 9 of the United Coast and Geodetic Survey contains the results of an investigation of the sources of the discrepancy in the values assigned to the ratio of the yard to the meter, made by O. H. Tittman, Assistant U. S. Coast and Geodetic Survey, in charge of weights and measures. The following interesting table is taken from the Bulletin. The third column contains the values of the meter expressed in inches, but referring to different metric and British units. The last column gives the results of the comparisons as reduced by Mr. Tittman, to the Committee Meter, C. M., in terms of the Imperial Yard.
Date. Authority.
1817-32 Hassler, 39,330917 39,36994
1818 Kater, 39,37079 39,36990
1835 Baily, 39,369678 39,36973
1866 Clarke, 39,370432 39,36970
1885 Comstock, 39,36985 39,36934
Indiscriminate mean, 39,36980