The plaintiff’s patent is for a tension apparatus for cable railways. Cables by úse stretch, and means inust be provided to take up the slack. It was usually done by a ‘weight suspended in a pit, and attached to the cable wheel. Manifestly the bottom of the pit was the limit of the tension. That reached, the cable either had to be shortened by removing a part or by taking one or more turns around a drum or pulley. As an improvement on this method, William Eppelsheimer, August 7, 1877, obtained a patent, (No. 193,939.) The object of his invention was to automatically keep the cable or rope at a certain tension. It was accomplished by the cable wheel being mounted on a car which moved on rails. This car also carried a shaft on which was keyed a drum and a ratchet wheel, which engaged in a rack on the rails on which the car moved. The weight is suspended in a pit as in the old method, and is attached to a drum passing over a fixed pulley. The operation is that, when the cable stretches by use, the weight pulls on the drum, which is prevented from revolving by a pawl, and the cable pulley car is moved in the opposite direction from the pull of the main cable. Should the stretching weight touch the floor of the pit by turning the shaft on which the drum is keyed, the stretching chain is shortened by winding around the drum. When the pull is by any cause by the main cable, the drum is made to revolve, to wind on it the stretching chain.

This was the state of the art when the patent sued on was granted, and it was hence contended that there is no invention in the latter. There are certainly similarities in it to the Eppelsheimer device, but there are differences- also. In both the tension on the main cable is ultimately maintained by a weight, but the ways of raising it are not the same. In the Eppelsheimer patent it is raised by the operator winding the chain on the drum by means of a crank. In the plaintiff’s patent it is raised by a car with a pulley moving backwards under the chain. There are other differences, and the testimony shows that they are more than formal. The result is a more automatic and compensating adjustment than obtained in the Eppelsheimer patent. The plaintiff’s is a practical machine, but Mr. Bell, defendant’s witness, and who devised its machine, hesitated to say that the Eppelsheimer device was a practical one, and admitted he would not have used its automatic devices. We must hold, therefore, and in this we are sustained besides by the presumptions which attach to the patent, that the plaintiff’s patent is so far different in kind and degree to that which preceded it as to constitute an invention.

Has the defendant infringed it? The plaintiff claims the invention to be a cable pulley having its axis journaled upon a car which moves on rails or timbers, which again travel on a second track. It is called in the patent a “secondary track.” In the defendant’s device part of the rails and timbers which appear in plaintiff’s device *385'are cut away, and the movable car which supports the cable pulley, and upon which it is journaled, as in plaintiffs patent, is let down so that the car which carries the cable wheel and the car (if it can be called a car, — in the plaintiffs patent the name is “rails or timbers”) which carries the chain wheel moves on the same track. This change involved minor alterations, which are not necessary to detail. It is manifest there is an infringement. The purpose, principle, and operation of the machines are the same, and the defendant’s escapes exact similitude ol construction to the plaintiff’s only by a few alterations. It is not a case of using the elements of a combination less than all. It is a case of using the same number of {dements, and altering the form of one, and not materially altering the relation of any to the others. The objection of defendant to the question addressed to the witness Bell, as to the function of certain parts of the plaintiff’s and defendant’s devices, is treated by counsel as involved in the other assignments of error, and must he considered as disposed of by the decision on them. Besides, if error, it cannot he said to have been a prejudicial one. Judgment is affirmed.