Electric Railroad Signal Co v. Hall Railway Signal Co

• Decision Date: 30 March 1885
• Citation: 29 L.Ed. 96,114 U.S. 87,5 S.Ct. 1069
• Parties: ELECTRIC RAILROAD SIGNAL CO. v. HALL RAILWAY SIGNAL CO. 1
• Court: U.S. Supreme Court

114 U.S. 87

5 S.Ct. 1069

29 L.Ed. 96

ELECTRIC RAILROAD SIGNAL CO. v. HALL RAILWAY SIGNAL CO.¹

March 30, 1885.

Chas. E. Perkins and G. H. Christy, for appellants.

S. E. Baldwin, for appellee.

MATTHEWS, J.

This is a bill in equity for an injunction to restrain the alleged infringement of letters patent No. 140,536 for an improvement in circuits for electric railroad signals, issued July 1, 1873, to Frank L. Pope, of whom the appellants, who were complainants below, are assignees. On final hearing the bill was dismissed by a decree now brought here for review by this appeal. The drawing which accompanies and illustrates the patent is as follows:

The following is the substantial part of the specification, together with the claims:

'My invention consists in a peculiar arrangement of electric circuits, in combination with a battery, and with two or more circuit-closers operated by moving trains or otherwise, whereby a series of two or more visual or audible signals, situated at intervals along the line of a railroad, may be operated by currents of electricity derived from a single barrery, thereby obviating the inconvenience and expense of employing, as heretofore, one or more separate batteries situated at or near each signal for the purpose of actuating the same.

'In the accompanying drawing, A, A, represents a portion of the track of a railroad. At intervals of, say, a mile, more or less, sections of the said track, a, a1 insulated from the remainder in a manner well understood, and therefore requiring no detailed description. B is a galvanic battery, of any suitable construction, and placed in any convenient location near the line of the railroad. Two wires or other conductors, C and Z, are attached to the positive and negative poles, respectively, of the battery, B, and extended to any required distance in a direction parallel or nearly so to the line of the railroad. The conductors, C and Z, may be placed on poles, and should be suitably insulated from each other and from the earth. The conductors, C and Z, are virtually prolongations of the positive and negative poles of the battery, B. Each of the insulated sections of track, a, a1 point at or near which it is desired to erect a signal, and any required number of these may be employed to meet the requirements of any particular case. M, M¹, and M² are the electro-magnets, which actuate or display the respective signals. The said signals may be of any suitable construction, and should be provided with some suitable means of retaining them in position or action after the circuit through the magnets, M, M¹, or M², has been interrupted. m, m¹, and m² are magnets so arranged as to release, reverse, or stop the action of said signals, which have previously been brought into action by the magnets, M, M¹, and M².

'The operation of the apparatus is as follows: Suppose a train moving along the track, A, A, from left to right in a direction indicated by the arrow. Upon reaching the point, a, the wheels and axles of the train will form an electrical connection between the opposite insulated rails, and a circuit will be formed between the conductor, C, and the conductor, Z, traversing wires, 1 and 2, magnet, M, and wire, 3, and the signal attached to M will consequently be displayed. Upon the arrival of the train at a¹ the same operation will be repeated, and another connection formed between C and Z, traversing the wires, 4 and 5, magnet, M¹, and wire, 6, while at the same time a portion of the current will traverse the branch-wire, 7, magnet, m, and wire, 8. Thus the signal attached to M¹ will be act ated, and simultaneously the action of the magnet, m, will release or reverse the action of the first-mentioned signal. Upon reaching the point, a², the closing of the circuit by the train will, in like manner, cause the signal attached to M² to be displayed, and the signal last displayed by M¹ to be withdrawn. In this manner any required number of such signals may be operated by means of a single battery.

'The respective resistance of the several circuits should be so adjusted that they will be as nearly as possible equal to each other, as a much more perfect action of the apparatus will be secured thereby.

'On a railroad having a double track two separate series of signals, one series for each track, may be connected with the conductors, C and Z, of a single battery, if required. If preferable they may be also operated by means of separate batteries and separate conductors. In cases where it is required to operate a large number of signals, extending along the road for a distance of many miles, the two conductors, C and Z, may be extended the entire distance, and a number of batteries attached at convenient intervals, say, for instance, from five to ten miles apart. The several batteries should all be placed with their positive poles in connection with the wire, C, and their negative poles in connection with the wire, Z, when they will virtually form one large battery, and the principle of operation will remain the same as that hereinbefore described.

'I do not desire to confine myself to the use of any particular form of visual or audible signals, nor to the particular devices herein described for closing the electric circuit at points from which a signal is to be operated. Instead of the circuit being closed automatically by the train itself, it may be closed by a signalman by means of a key or switch, or otherwise.

'I claim as my invention: (1) The battery, B, in combination with the positive and negative conductors, C and Z, two or more electro-magnets, M, M¹, M², for actuating, or causing to be actuated, visual or audible signals, and two or more circuit-closers, a, a1 a railroad, substantially as and for the purpose specified. (2) The battery, B, in combination with the positive and negative conductors, C and Z, two or more electro-magnets, m, m1 releasing or reversing visual or audible signals, and two or more circuit-closers, a1 railroad, substantially as and for the purpose specified. (3) The combination of the battery, B, conductors, C and Z, circuit-closer, a, and electro-magnet, M, for actuating a visual or audible signal, with the circuit-closer, a¹, wires, 5, 7, and 8, and electro-magnet, m, for reversing, releasing, or stopping said signal, substantially as specified.

Among several defenses set up in the answer, the two chiefly relied on were—First, that Thomas S. Hall, and not Pope, the patentee, was the first inventor of the improvement claimed, and, second, that the devices used by the defendants were not an infringement of the patent. The decree below was based on the first of these defenses alone, the circuit court finding that Hall was entitled in law to priority of invention; but we have not found it necessary to discuss the questions of fact and law embraced in this issue, as we have concluded to dispose of the case upon the ground that the defendants did not, by the devices used by them, infringe for patent of the complainants. THESE DEVICES ARE ILLUSTRATED BY A DRAWING, of which the following is a copy:

This diagram represents the plan of electric railroad signals, placed and put in practical operation, by the defendants, on the line of the Eastern Railroad near Boston, prior to the bringing of this suit. In comparing it with the drawing annexed to the patent, it is to be r membered that the latter represents a series of double signals in succession on the line of a railroad track, divided into blocks, while Exhibit C represents but one pair of such signals in one such block. To make it correspond with the other, as a representation, it should be imagined as being repeated in several successive blocks, constituting portions of one circuit, closed at fixed points by circuit-closers for that purpose. Mr. Pope, the patentee, drew this diagram, and, as a witness on behalf of the complainants, explains it in comparison with the plan described in the patent, with a view to establish their identity. He says:

'I have made a diagram which exhibits the apparatus which I examined, or so much of it as is material to this case, which I annex, and is marked Exhibit C. A battery of perhaps one hundred cells is placed in the station building at Chelsea. One pole of this battery—I think the negative pole—is connected to the earth. A conductor is attached to the other or positive pole of the battery, consisting of an insulated wire, extending along parallel with the track upon poles. This wire which I examined, extended to wards Boston, the end remote from Chelsea being disconnected, or, as it is termed, open. A second conductor, consisting of another similar wire insulated and attached to the same poles, was arranged parallel to the first one. The second wire was open at Chelsea, and connected with the earth at its remote end. The first-mentioned wire I have shown in the diagram, and marked 'positive conductor;' the second wire is marked 'negative conductor.' At a short distance from the station a semaphoric signal is placed, consisting of a red disk balanced upon a lever. This was placed in the cupola of a small building at the side of the track. An electro-magnet was arranged with its armature attached to said lever, so that when brought into action the red disk on the other end of the lever would be moved into a position to render it visible through an opening in the cupola. A latch or detent was placed in a position to fasten the lever after the action of the magnet had ceased, and thus continue the exhibition of the signal. A circuit-closer was placed upon the track at a point near the signal, which consisted of a lever so placed as to be depressed by the wheels of a passing train, which movement caused the circuit to be closed by pressing two springs together. When the circuit was thus closed by a passing train a connection was formed between the positive and negative conductors, and the electric current, in passing from one to the...