This is an action at law to recover damages for the alleged infringement of letters patent No. 257,943, issued May 16, 1882, to Philip Hinkle, of San Francisco, Cal., for "an improvement in freight and passenger elevators.” The invention claimed by Hinkle is stated in the specifications of the patent, as follows:

The principle of this double-acting machine is illustrated in the specifications as follows:

The claims of the patent are:

The defendant in error uses what is known as the “Frazer Elevator.”

The assignments of error present two questions for the consideration of this court:

*157 1. It is claimed that the court erred in admitting in evidence, against plaintiffs objection, the letters patent No. 185,270, issued December 12,1876, to W. D. Andrews, for an improvement in hoisting apparatus, which, it is asserted, was claimed by the defendant to be in anticipation of plaintiff’s patent, on the ground that no notice had been given to plaintiff that such patent would be offered in evidence, as required by section 4920 of the Revised Statutes. It is true that counsel for the defendant insisted that the Andrews patent was a “full anticipation of the plaintiff’s patent.” But it was not admitted in evidence for the purpose of proving anticipation. The facts are that upon the cross-examination of Mr. Boone, a witness on behalf of plaintiff, certain questions were asked by defendant’s counsel relative to the Andrews patent, which simply tended to show the state of the art, viz. that in the Andrews patent there was a counterpoise for the purpose of balancing the car and its load, — in other words, that there was in the Andrews patent the overbalance weight, which constitutes but one of the elements of the claims in plaintiff’s patent. But, in any event, it is clear that no possible injury could have resulted to the plaintiff, even if the Andrews patent had been admitted in evidence, for the reason that the court did not base its instruction to the jury on the ground that plaintiff’s patent had been anticipated. The validity of plaintiff's patent was not disputed. The only question considered by the court was whether, upon the facts introduced in evidence, any infringement of plaintiff’s patent was shown. When plain 1 iff! closed its case the defendant moved the court to instruct the jury to ibid a verdict for the defendant “upon the ground that the plain tiff has not proved any infringement,” and upon the further ground that plaintiff had not shown any new invention covered by the claims of its patent. The last ground of this motion was expressly overruled by the court, and the motion, upon the first ground, was granted. From the facts shown by the record, it is manifest that the first assignment of error is wholly insufficient to justify a reversal of the case.

2. Did the court err in instructing the jury to find a verdict for the defendant upon the ground that the plaintiff failed to prove any infringement of its patent?

It was claimed by the plaintiff in the court below that there was something new produced in plaintiffs patent, on account of the overbalance counterweight. It was there, as here, argued that the only difference between the Frazer elevator, used by the defendant, and Hie elevator shown in plaintiff’s patent, was that instead of the single drum, worm wheel, and worm shown in plaintiff’s pa tent for transmitting the power and motion from the motor to the cage and counterbalance ropes, the defendant’s machine has substituted a different form of a transmitting device. The testimony was mainly directed to this issue, and as to whether the devices or elements used by the defendant’s machine were, or not, the mechanical equivalents of those described in the plaintiff’s patent. The experts introduced by the plaintiff testified generally that the device in the Frazer elevator, which, it is claimed, was substituted *158 for tbe single drum, worm wheel, and worm in plaintiff’s patent, was, in effect, the mechanical equivalent of those devices, and that it performed the same duties in substantially the same way. Upon this testimony the plaintiff argues that the only question in the case was one of fact, — whether or not the substituted element of the combination of the Frazer elevator was a mechanical equivalent of the elements shown in plaintiff’s patent for performing the same duty; that, the testimony of the experts being to the effect that it was, it became the duty of the court to submit that question of fact to the jury; and that the court therefore erred in instructing the jury to find a verdict for the defendant. To sustain-this proposition, counsel cite Tucker v. Spalding, 13 Wall. 455 ; Keyes v. Grant, 118 U. S. 36 , 6 Sup. Ct. 974; Humiston v. Wood, 124 U. S. 12 , 8 Sup. Ct. 347; Royer v. Belting Co., 135 U. S. 319 , 10 Sup. Ct. 833; Coupe v. Royer, 155 U. S. 565 , 15 Sup. Ct. 199. It was admitted by the defendant at the trial that there is an overweight counterbalance in the Frazer elevator, and that its office and function are exactly the same as is shown in plaintiff’s patent. It would necessarily follow that, if the plaintiff’s patent is susceptible of being so construed as being for that device alone, then, of course, it would follow that an infringement was clearly proved, and the judgment should be reversed. But an examination of plaintiff’s patent discloses, upon its face, the fact, beyond any possible controversy, that it does not cover the use of an overbalance counterweight as an independent device. Both of its claims are for a combination of elements. The overbalance counterweight is claimed as one mechanical element in a combination with other elements specified in the ciaims. It certainly cannot consistently be claimed that Hinkle invented the overbalance counterweight. He was introduced as a witness, and upon Ms cross-examination said:

This result ordinarily follows whether there is any testimony upon the point or not. When a specific element is not claimed as a device by itself, it is, in effect, admitted that the particular element is old, and was not invented by the patentee. In 3 Rob. Tat. § 923, it is said:

In the Corn-Planter Patent, 23 Wall. 181, 224 , the court said:

See, also, Rowell v. Lindsay, 113 U. S. 97, 102 , 5 Sup. Ct. 507, and authorities there cited.

Every element of the combination is presumed to be material, and it is the combination of the elements that is new. As was said in Water-Meter Co. v. Desper, 101 U. S. 332 , 337:

Plaintiff’s patent being for a combination, it necessarily follows that there cannot be any infringement, unless the Frazer elevator contains all of the elements of the combination in plaintiff’s patent, or their mechanical equivalents. Norton v. Jensen, 33 C. C. A. 141 , 90 Fed. 415, 429 , and authorities there cited.

In De Loriea v. Whitney, 11 C. C. A. 355, 364 , 63 Fed. 611, 620 , the court of appeals said:

There is a clear distinction drawn, in all of the authorities which discuss the question, between a pioneer invention and an invention merely of improvements by a combination of mechanical devices. A patentee who is the original inventor of a device or machine — a pioneer in the art — is entitled to a broad and liberal construction .of his claims: but an inventor -who only claims to be an improver is only entitled to what he claims, and nothing more. In other words, the original inventor of a device or machine has the right' to treat as infringers all who make or use devices or machines operating on the same principle, and performing the same functions by analogous means or equivalent combinations. "But if the invention claimed be itself but an improvement ón a known machine, by a mere change of form or combination of parts, the pat-entee cannot treat another as an infringer who has improved the original machine by use of a different form or combination performing the same functions. The inventor of the first improvement cannot invoke the doctrine of equivalents to suppress all other improvements which are not mere colorable invasions of the first.” McCormick v. Talcott, 20 How. 402, 405 ; Norton v. Jensen, 33 C. C. A. 141 , 90 Fed. 415, 422, 423 , and authorities there cited.

*160 Touching the question as to whether the Frazer elevator contained all the elements, or the equivalents thereof, of plaintiff’s patent, and the effect of the testimony of the experts in regard thereto, the circuit court, among other things, said:

Reading the plaintiff's patent in the light of the conditions and usages prevailing, at the time of its inception and issuance, in the art to which the invention relates, and upon examination of the models of the respective machines exhibited to the court, we are of opinion that the conclusions arrived at by the court are correct. The motive power of the two machines is radically different, in their construction and mode of operation. The elements mentioned in the claims of plaintiff’s patent are not all found in the Frazer elevator. The plaintiff’s elevator operates with a single motor and with a worm gear. The Frazer elevator has no worm gear, and is so constructed that it could not be operated either with a worm gear or with a single motor. The plaintiff’s elevator has a drum, around which a rope is wound and unwound. The Frazer elevator has no such drum. In the plaintiff’s elevator the drum which transmits the power from the driving motor turns in one direction to raise the cage, and must1 reverse and turn in the opposite direction to lower the cage. In the Frazer elevator there is no drum or pulley, transmitting the power from the motors, that turns in one direction to raise the cage, and then reverses and turns in another direction to lower the cage. In the light of these and other different mechanisms, which need not be stated, we are of opinion that, notwithstanding the general opinions and conclusions expressed by the expert witnesses, the plaintiff’s patent is not infringed by the use of the Frazer elevator.

The court certainly has the unquestioned right to draw its own conclusions from an exhibition and inspection of the respective machines, or models thereof, as well as from the opinions of expert witnesses. It is not bound to accept such testimony as conclusive. The Conqueror, 166 U. S. 111 , 131, 17 Sup. Ct. 510. It considers the facts upon which the opinions of the witnesses are based, and determines *161 from all tbe evidence in tbe case whether the conclusions given by the witnesses are sound and substantial. The value of expert testimony generally depends upon the facts stated as a reason for their opinions and conclusions. Green v. Terwilliger, 56 Fed. 381, 394 ; 1 Tayl. Ev. § 58. More weight is given to the testimony of a witness based upon facts within his own knowledge and experience than to the testimony of a witness which is “largely the assertion of a theory.” Béné v. Jeantet, 129 U. S. 683, 688 , 9 Sup. Ct. 428. In 3 Rob. Pat. § 1012, the author, in discussing this subject, says:

See Walk. Pat. (2d Ed.) § 498.

The law is now well settled that the trial court not only has the power, but it is its duty, where the evidence is insufficient to support a verdict in favor of the plaintiff, to instruct the jury to find a verdict in favor of the defendant. This rule applies to patent as well as other cases, and is as applicable to the question of infringement as to any other material or controlling question involved in the case. In 3 Rob. Pat. § 1014, it is said:

•‘If an inspection of the invention practiced by tbe defendant, in connection with the one described and claimed in the patent, satisfies the court that there has been no infringement, * * * there is no occasion for extraneous evidence, and the court should direct the jury to return a verdict for the defendant without further inquiry. * * * Neither a court nor a jury are permitted to follow the guidance of any expert, in defiance of the results of practical operation and experiment, nor against conclusions derived by necessary inferences from established facts.” Walk. Pat. (2d Ed.) § 536; Fond du Lac Co. v. May, 137 U. S. 395, 403 , 11 Sup. Ct. 98; Railway Co. v. Rowley, 155 U. S. 621, 630 , 15 Sup. Ct. 224; Black Diamond Coal-Min. Co. v. Excelsior Coal Co., 156 U. S. 611, 618 , 15 Sup. Ct. 482; De Lorica v. Whitney, 11 C. C. A. 355 , 63 Fed. 611, 617 ; Cramer v. Fry, 68 Fed. 201, 212 ; Chapman v. Lumber Co., 32 C. C. A. 402 , 89 Fed. 903, 905 , and authorities there cited.

This principle is recognized in Royer v. Belting Co., 135 U. S. 319 , 10 Sup. Ct. 833, and is not denied in any of the other cases cited and relied upon by plaintiff. The judgment of the circuit court is affirmed, with costs.