At the Bisley rifle meeting in England last year, great interest was centered in a new type of target that has been invented by Lieut.-Col. George A. Peters of the Ninth Toronto Light Horse for the automatic indication by electrical agency of the effect of shots. This apparatus has been designed for the purpose of securing an immediate and accurate record of the shot fired, dispensing with the necessity and cost of constructing a mantelet for the protection of the markers, and also with the attendance of markers, two of whom are ordinarily required in the operation of the usual balanced type of target. In this self-registering electric target there is a face-plate of solid steel which, through the agency of certain mechanical devices distributed over its posterior surface, is capable of responding in sections. When a bullet strikes any part of the target, the corresponding unit behind the plate is set in operation, in such a way that an electric circuit is closed, and a disk on the corresponding part of an indicator or annunciator, similar to that employed in connection with electric bells, is exposed at the firing point. The apparatus illustrated in the accompanying engravings is designed for use in indoor or miniature ranges, but the principle of design and the operation are precisely the same as in those for use on outdoor ranges. The main framework of the target is composed of a pair of substantial upright standards connected by cross-beams, and furnished with bases which are firmly bolted to a square horizontal platform of heavy timber. In the case of those adapted to miniature range practice, as illustrated, the target is carried upon a heavy iron pedestal. The target itself is swung upon the standards by means of a rocking frame, the front arms of which are mounted on pivots near the four corners of the plate. The rocking frame is designed upon the principle of a parallel ruler or a system of parallel motion levers by means of which the plate as a whole can be raised and lowered in the direction of the arc of a circle having a radius equal to the length of the anterior arms of the rocking frame this length is also equal to the radial length of the hammers without altering the vertical position of the frame. By this means the plate may be brought nearer to or removed farther from the back plate supporting the hammers without disturbing the vertical position. The presence of the rocking frame enables the target to be made adjustable as regards sensitiveness for various ranges, weights, and velocities of different ammunition, while it is also through the movement of this section that the working integrity of all parts of the target may be tested. The target plate is constructed of three layers of chrome steel, alternately hard and soft, as adopted in the laminated construction of burglar-proof safes. When the range exceeds 100 yards, but little impression upon its surface is made by the bullets. The plate supporting the moving hammers is composed of mild steel about % inch in thickness, and is rigidly bolted to the cross-beams between the standards. It is pierced by a series of oblong slots for the reception of the hammers, which are supported by pairs of lugs or brackets obtained by simply bending up the strips of plate from the sides of the slot. The number of hammers adopted varies according to the size of the target. The target required for indoor or miniature range practice is only 15 inches in diameter and 37 hammers are employed, while in a target 4 feet in diameter 61 hammers are required. The hammers are placed in concentric circles about the central hammer, which corresponds to the "bull's eye," there being 6 hammers in the "inner" circle, 12 in the "magpie" circle, 18 in the "outer" circle, and an additional circle of 24 outside of these which are grouped for working purposes with the hammers of the "outer" circle. In a 6-foot target for use at 500, 600, and 800 yards, respectively, which is the largest yet made, and which has recently been installed at the Toronto Rifle Ranges, the same number of hammers as in the 4-foot target is utilized, the hammers being placed farther apart. Each hammer is supported upon the back plate by a pivot which passes horizontally through it near its rear extremity, and rests simply by its own weight upon the lugs or brackets already described. Thus each hammer can easily and readily be removed by hand when required for examination or repair. The opposite end of each hammer is provided with a rounded head, and this rests normally against the rear face of the target plate. The backward motion of the hammer, however, is regulated by means of a shoulder which insures that the center of gravity of the hammer piece is always in front of Its supporting pivot, so that after being driven backward by the impact of the bullet striking the target plate it immediately falls back into its normal position against the target plate. The end of the hammer projecting beyond the point where it is pivoted Is provided with a tall or spur which projects almost vertically upward, when the hammer is In the normal position. When, however, the hammer is forced backward by the Impact of the bullet, this spur moves In a circular direction bacK-ward and establishes sliding electrical contact, with a slender Insulated brass spring connected by wire with the annunciator. This contact continues through a length of time corresponding to the end of the rearward movement of the hammer, and also to the beginning of its return movement It will thus be seen that a length of contact is obtained which Is considerably in excess of that required to cause the corresponding indicator upon the annunciator to drop. One of the leads of the electric cable is soldered to each brass contact, while earthing is obtained by soldering the wire to some portion of the supporting plate, thereby forming a complete electrical circuit broken only between the hammer spurs and their respective brass springs. The battery Is located at the annunciator end of the cable. When one hammer or more is moved and an electrical connection established, the corresponding magnet or magnets on the annunciator are energized and the indicator or ind'-cators fall, recording the result of the shot fired. The annunciator is constructed of galvanized iron with a weather-proof case and Incloses a number of electro-magnets arranged in concentric circles to conform to the arrangement of the hammers of the target. Each of the electro-magnets when energized operates a very simple form of corresponding gravity drop. The groups of indicators in the respective rings carry the customary scoring numbers. The annunciator is equipped with a restoring mechanism which is operated by a strong magnet, so that after the drop or drops have fallen, the simple pressing of a button resets the apparatus. When a bullet strikes the plate, no appreciable movement of the whole results from the Impact, but the Impact sets up a bulging over a certain circumscribed area, around the point where the missile strikes. Should this point be immediately opposite one of the hammers, that hammer only will be forced backward. At the same time It is obvious that the area to which any hammer will respond will be circular in outline, and it is equally obvious that the disposition of the hammers must be such that the circular areas must overlap one another, so that no dead spaces are I ft, which would be irresponsive to the impact of the bullet. Therefore, should the bullet strike the target in the space where two hammer areas overlap, both corresponding hammers will be affected and driven back, and their corresponding indicators on the annunciator will fall. Similar results will attend the striking of the target at those places where three and even four fields of Influence overlap, so that it is possible for four indicators to be exposed as the result of one shot. At first sight this circumstance might appear to militate against the utility of the apparatus for scoring purposes, but as a matter of fact It assists appreciably in the localization of the shot. For Instance, in a target having 37 hammers, if It were required that each shot should be responded to by the fall of one drop only, then there could be only 37 points of localization; but when It Is remembered that the location of each shot is approximately opposite the hammer when only one drop falls, and In the case of the bullet hitting the target mid-way between two hammers when two indicators fall, and so on with three and four drops, the number of points of localization becomes considerably Increased, aggregating over 150 different points. The degree of accuracy of localization by means of this apparatus will be readily appreciated when It Is remembered that In regard to the "bull's eye" alone there are thirteen different localizations that can be automatically indicated in the circular area 7 inches in diameter at a range of 200 yards. Ricocheting shots, which often enter into the scoring with the canvas targets, are with this apparatus eliminated, since they have not sufiBcIent momentum when finally striking the target to force the hammer back far enough to make the necessary electrical contact. At the present time, all "bull's eyes" are placed on an even basis in scoring, and In rifle competitions "ties" often result, simply because there is no fair way of discriminating between the marksman who strikes the dead center of the "bull's eye" and the one who strikes it upon the circumference of its area. With this apparatus, however, it is quite easy to make such distinctions with perfect fairness. Owing to the overlapping of the respective fields of influence, Instead of there being only four zones corresponding to "bull's eye," "Inner," "magpie," and "outer," respectively, there are seven distinct fields. Upon rifle ranges where a series of targets may be required, each target Is provided with its own annunciator at the firing line, but a cable with a single set of wires will suffice for an unlimited number of targets, provided there are as many wires in the cable as there are hammers or groups of hammers in any one target, besides a ground wire for each target. Thus a range having 10 targets and 37 hammers upon each would require a cable with 47 wires. This equipment would enable all the targets being in operation at the same time without any possibility of one interfering with the other, since it Is apparent that each annunciator will only respond when the circuit is completed through its own ground wire. For protecting the cable from stray bullets It should be burled at a depth of about 8 inches.
This article was originally published with the title "The Peters Self-Registering Electric Target for Rifle Ranges" in Scientific American 97, 22, 395-396 (November 1907)