(after stating the facts as above). The combination here patented consists of the following elements: First, a railway track; second, stationary means of electric supply; third, electrical conductors extending from said means of electric supply along the lines of the track, and consisting wholly or in part of the rails thereof; fourth, vehicles moving along said track; fifth, electrodynamic motors, whose coils are constantly excited so long as the poles of said motors are in circuit with the means of electric supply fixed upon said vehicles for imparting motion thereto; and, sixth, wheels supporting said vehicles upon the track, and also serving to maintain continuous electrical connection between said means of electric supply and motors, substantially as set, forth. As early as 1.840, a patent was issued to one Pinkus, in England, for the application of electricity to locomotion of vehicles, including railway cars. In the specifications he provided a stationary source of supply of electricity, a motor upon the car, to tie actuated by the electric current, and two parallel electrical conductors extending along the track between the rails to maintain the electrical circuit between I lie stationary source of supply and the motor. The connection between the car and the conductors was maintained by two so-called electro-magnetic slides, which, being attached to the car, were intended to trail or slide along on the conductors, maintaining constant contact and an unbroken circuit. Five years later — in 1845 — an article was published in the Mechanic’s Magazine, in which it was suggested that a plan for an electric railway was feasible in which there should be a stationary source of supply, and a motor upon the car, and that the electrical circuit between the source of supply and the motor on the car might be maintained by using the rails of the *620track and the wheels as conductors. In 1847, a Dr. Colton, a popular lecturer on scientific subjects, in order to show the possible applications of electricity as a force, devised, in conjunction with one Lilly, a machinist, a model of an electric railway. He built a circular track six feet in diameter, insulated the rails, placed thereon a car upon which was a motor consisting of two electro-magnets with an armature over each, by the reciprocating operation of which; motion was given to a crank that turned cogwheels geared with the wheels of the car. The current was carried by a wire from the positive pole of the battery to one of the rails of the track, through the wheels traversing that track to the motor, and thence through the wheels on the other rail to that rail, and thence by wire to the battery again. This model, in operation, was exhibited, and its principle explained, by Dr. Colton, in all the large cities of the country, to 50,000 people, and descriptions of it appeared in all the daily papers of that day and in the Scientific American and other scientific publications. In 1853 an English patent was issued to Dugmore and Millward for electric signaling from one train to another, in which is suggested as a practical alternative mode of carrying the current from one train to the other-the use of the rails of the track and the wheels of the locomotive on each train to maintain the electrical circuit. In 1855, in a patent issued to one G-uyard for a method of signaling between trains, as an alternative method, is suggested a circuit consisting of an overhead wire, a contact device on the cars,. and a return by way of the wheels and the rails and the earth. In the Wesson’s United States patent, issued in 1857, for communicating ■ signals from a station to a moving train, the suggestion is made that the electricity could be carried to the train by means of the insulated tracks. In an English patent to Clark,. of 1864, for electric generators and motors, rails and wheels were used to carry the current from a stationary source of supply to the motor on a railway car and back again. There are other suggestions of the same kind between 1864 and 1879, when Green applied for the first patent in suit.

Counsel for complainant object vigorously to all these references to the prior art as grounds for denying novelty to Green, for the reason that none of the devices were operative, or commercially available for the construction of a street railway. This is probably true. Prior to 1872, the expense attending the production of electricity sufficient to run a street railway by any of the then known methods was so enormous as to make an electric railway an impossibility. It was not until 1867 or 1868 that a practical machine for turning electricity into propelling force was devised which was powerful enough to move the modern street car. Given a practical stationary source of electrical supply, and given a practical motor, the prior art was full of practical suggestions of the method Green afterwards adopted by which the current might be carried from one to the other without interrupting the progress of the traveling car. Green -does not narrow his combination to the use of any particular method of producing electricity, but includes therein any well-known method. He does narrow somewhat his motor to one whose coils *621are constantly excited so long as the poles of the motor are in circuit with the means of electric supply. This was, however, the common and best class of motor in use then, and is still. Green does not and cannot claim in this patent any novelty for either his source of supply or his motor. The gist of his invention, if he made any, is in the system or plan by which he brought into correlation a practical stationary source of electricity and a practical electrical motor for changing the current into propelling force. After dynamic-electric machines and electric motor's were invented which would do the work required, then Green united them by a plan or system which had previously been unsuccessful solely because the electric machines then known were defective. Did it involve an exercise of the inventive faculty to substitute good machines in the combination for defective ones when the fund ions to be performed had been clearly outlined in the prior art? Was there anything new discovered in the quality of the electric fluid to be conveyed which made the problem of conveying it from a practical electricity-making machine to the practical force-producing machine on the moving car any different from the problem when the machines were defective and feeble, but the possibility of their perfection veas conceived of, and confidently predicted? We have found nothing in the record, or in the arguments or briefs of counsel, or In a careful consideration of the patents themselves, that will justify an affirmative answer to these- questions. The additional element of a current controller in the combination of the second Green patent, and the suggestion therein that a dynamo mi slit be used as a source of supply, do not save that patent from the fatal defect of a lack of invention. As far back as 1840, the Pinkus patent included in the combination there proposed a motor which had a current controller. The advantage of means for reversing the current and the motion of the car would seem to have been so obvious that it could not have involved an exercise of the inventive faculty to add it here when such means had been shown in the prior art.

There is satisfactory evidence that Green made a working model of his electric railway in 1875, and (hat he exhibited it to many thousand people at his shop. Green says that he conceived his invention in 183(5, when he constructed and operated a small circular electric railway very like that of Lilly and Colton. Defendants attack complainant's pa tent, which was not applied for until 1879, on the ground that his railway of 1875 was in public use more than two years before his application. Without passing on this issue, it suffices to say that Green’s earlier conceptions of his plan do not aid his case, for the Pinkus, the Lilly and Colton, and the Bugmore and Millvvard suggestions of a system including a stationary source of supply combined with a motor on the car and an electrical circuit of the rails and wheels were made prior, even, to the first conception by Green of liis system in 1856. It cannot be too emphatically stated that Green’s claims in these patents are for combinations of parts, and not for the parts themselves. He had secured a patent for a motor prior to making his application for the first of the patents now in suit, but the invention involved in devising that ma*622chine is of no moment in considering the question of invention in the combination, for it is not claimed that the peculiarities of that motor presented any new problem of carrying the current to the poles of the motor from a stationary source of supply. We think, therefore, that Green’s patents are void for want of patentable invention.

But, even if Green’s patents could be sustained, it could only be on the ground that the combinations patented are to be distinguished from those shown or obviously suggested in the prior art by the fact that with the new machines for making electricity, and new machines for converting it into propulsive force, the combination was operative, and could be actually used to run a street railway. The scope accorded to the claims must, therefore, be limited strictly to the combination disclosed in his patent, which could be made practically operative by following the directions of the specifications. The only combination thus shown in the specifications is one in which the electric fluid is carried by one insulated rail and the wheels on it to the motor, and back by the wheels on the other rail, and that rail either insulated or grounded so as to permit either a complete metallic circuit or an earth return. There is a suggestion in both patents that independent conductors may be used, but there is no suggestion as to how the contact between those conductors and the moving car is to be maintained, unless the specifications are to be construed as meaning that conductors are to be used so connected with the rails that the wheels may still be used as contact devices. The defendant does not insulate either rail, and uses an overhead wire with an under-running trolley contact. It is contended by counsel for the complainant that it is permissible to imply in his specifications the use of any contact device then known in the art for keeping continuous connection between the independent conductor and the moving car. What contact devices were then known in the art? We are referred to the one shown in the Pinkus patent, called by the patentee an “electro-mag-netic slide.” But it is quite clear that such a slide could not be used with an overhead wire used in defendants’ railway without changes involving much more than mechanical skill. And it is quite probable that the Pinkus device, even as used, would not be of any practical value. The fact is that in 1879 there was no contact device known in the art, capable of, use with an independent conductor, especially an overhead wire, which had been proven to be practically operative. Green had never used one on his railway models, and, although he shows a sketch, made, as he says, and as attesting witnesses say, in 1871, in which an overhead wire and a contact device of double rollers are shown, he never made such a conductor, or such a contact device, or demonstrated their operativeness; and when he applied for a patent he failed to disclose either overhead wire or contact rollers. The history of the art of electric railways, is made up in three great steps: First, the invention of a machine or motor for converting the electric fluid into propulsive force without material loss; second, the invention by Gramme of an electric generator which would produce the electric fluid in great quantity and high intensity at such a price as to make the operation of heavy *623street cars commercially possible and profitable; and, third, the invention of a practical contact device for keeping constant the connection between the overhead wire used for carrying the positive electricity and the moving ear. This last device was invented by Van Re Pottle in 1886 or 1887, and is called the “under-running trolley.” Other contact devices were invented and known before Van Re Poele's, but, although cars could be moved by them, they did not prove to be efficient, or really practical. When Green applied for his patent, in 1879, so far as this record shows, there was no operative and practical contact device known to the art for connecting moving cars electrically with an overhead wire. It therefore follows that the indefinite suggestion of independent conductors in Green’s patents cannot be enlarged or pieced out by reference to the art to make an operative combination of that which we find in defendants’ railway, to wit, a stationary source of electrical supply, a circuit consisting of an outgoing current to the car by an oyer-head wire and a suitable contact device, and a return circuit by the wheels and the rails or the earth. A careful reading of the history of Green’s patent in the 12 years his application was pending in the patent office, leaves no doubt in our minds that the combination for which Green .intended to procure a patent, and the only one he did intend to patent, and the only one he was entitled to have patented, if any, was a circuit in which the rails were to form the conductors, and the wheels were to be the collectors or contact devices. The really accidental reference to independent conductors contained in the original application of Green -was made the unfounded basis as the art progressed, and as the fact that success -was to lie witli the overhead conductor became plain, for changes of language in the specifications and claims which give color to the argument that the combination intended and disclosed by Green when he filed his application really included independent conductors and other contact devices than the wheels. We concur, therefore, in the view of the judge of the circuit court that the defendants’ railway does not infringe the patents of the complainant. The decree of the circuit court dismissing the bill is affirmed.