revenues, which provides a mode in which the mortgagee shall take possession, and, until that mode is availed of, leaves the tolls and revenues in the control of the mortgagor, to be disposed of as he sees fit. Galveston R. R. v. Cowdrey, 11 Wall. 459; Gilman v. Illinois & M. Tel. Co. 91 U. S. 603; American Bridge Co. v. Heidelbach, 94 U. S. 798. But by the statutes of the state of Maryland relating to the Chesapeake & Ohio Canal Company, and the mortgages executed pursuant to those statutes, the application of the tolls and revenues of the canal was not left to the disposal of the corporation. The state of Maryland, regarding the construction and maintenance of the canal as an object of great importance and benefit to the public, had lent to the canal company large sums of money, and subscribed for a majority of its stock, and, to secure its loans and investments, had taken from the company mortgages upon the canal and all its tolls and revenues.

By the statute of 1844, c. 281, the state authorized the company, in order to obtain additional means, to issue bonds secured by mortgage to trustees of its net tolls and revenues; the state waived its own lien upon the gross revenues so far only as to subordinate it to the lien of that mortgage; subject to that lien, the state took a new mortgage as additional security for the repayment of its original loan to the company; and the statute, under and pursuant to which these two mortgages were executed, and to which each was made subject, expressly provided that the company should have authority to use and apply so much of the gross tolls and revenues as might be necessary to keep the canal in repair, to provide the requisite supply of water, and to pay salaries and current expenses. The necessary effect of this arrangement was for the promotion of the public object as well as for the ultimate benefit of the mortgagees, to appropriate the tolls and revenues in the first in-, stance to the payment of necessary repairs and expenses.

in-g

The debt of the judgment creditor in this case was a general debt of the company, and not a bond secured by the trust mortgage, nor a debt contracted for repairs or salaries, or other current expenses. It is alleged in the bills, and admitted by the demurrers, that the creditor, at the time of contracting his debt, had notice of all the charges, liens, and duties affecting the tolls and revenues, and especially of the provision by which they were appropriated, in the first instance, to the payment of necessary expenses. And the money of the corporation, which he seeks to apply to the payment of his debt, is needed for those expenses. It follows that the judgment creditor has no equity, and that the state of Maryland, and the trustees for bondholders, whose security will be affected by the diversion of this money from its lawful object, are entitled to injunctions. This conclusion accords with the adjudication of the court of appeals of Maryland in Brady v. State, 26 Md. 290, and with the opinions expressed by that court in earlier and later cases. Boyd v. Chesapeake & Ohio Canal Co. 17 Md. 195; Virginia v. Same, 32 Md. 501. Decree affirmed.

(114 U. S. 87)

ELECTRIC RAILROAD SIGNAL Co. v. HALL RAILWAY SIGNAL Co.1 (March 30, 1885.)

1. PATENT LAW-ELECTRIO RAILWAY SIGNALS.

Hull's patent for electric railroad signals does not infringe the Pope patent No. 140,536, issued July 1, 1873, one proceeding upon the idea of unequal currents to be afterwards equalized, the other adopting and embodying the idea of avoiding the necessity of subsequent rectification by an original adjustment of equal resistance. The difference is inherent in the two combinations, and is substantial.

2. SAME-WHAT CONSTITUTES IDENTITY OF INVENTION.

To constitute identity of invention, and therefore infringement, not only must the result obtained be the same, but in case the means used for its attainment is a

'S. C. 6 Fed. Rep. 603.

combination of known elements, the elements combined in both cases must be the same, and combined in the same way, so that each element shall perform the same function provided, however, that the differences alleged are not merely colorable according to the rule forbidding the use of known equivalents.

Appeal from the circuit court of the United States for the District of Connecticut.

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 battery, 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, a2, are electrically 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, a2, etc., is placed at some 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 actuated, 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 herein before 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, a2, placed at intervals along the line of 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, m2, for releasing or reversing visual or audible signals, and two or more circuit-closers, a1, a2, placed at intervals along the line of a 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 the 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 remembered 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. v.58-68

Chelsea Depot