that neither the first nor the second specification could be rightfully regarded, as "inoperative or invalid," for want of precision and clearness, than that there was an important variance in the second from the first, or in the third from either. [French et al. v. Rogers et al., C. C. Pa., Grier and Kane, Jj., Nov. 1851.

III. Infringement of Patent Rights.- Damages.

1. The sale of the product of a patented machine, is not an infringement of the right.

M'Alpin, 3 M'Lean, 427.

[Boyd v.

2. But if the person who sells is connected with the use of the machine, it may be an infringement.. [Ibid.

3. Woodworth's right consists of a combination of known mechanical powers. [Ibid.

4. The use of any part of these, less than the whole, is no infringement. [Ibid.

5. To constitute an infringement, the defendant must have used the same combination, constructed and operating substantially in the same way. [Gorham v. Mixter et al., Sprague J., C. C. Mass., 1848.

6. Whereas, if he had used but two of the three elements of combination, it was not an infringement. [Ibid.

7. A mere change in form or proportions, or substitution of mechanical means, or equivalents, in any one or all the elements, producing the same result, would not constitute a substantial

difference within the meaning of the patent law. [Ibid.

8. Nor would it be a difference in infringement, that the party had added to the combination, or any elements thereof, and made improvements, provided they used plaintiff's combination, constructed and operating substantially in the same way. [Ibid.

9. Such additions and improvements, though meritorious, give no right to appropriate what belongs to another, without making compensation. [Ibid.

10. The plaintiffs in the Circuit Court, claimed damages for the infringement of their patent for a "new and useful improvement in the construction of a plough." The claim of the patentees was, for the combination of certain parts of the plough, not for the parts separately. The Circuit Court charged the jury, that unless it is proved that the whole combination is substantially used in the defendant's plough, it is not a violation of the plaintiffs' patent, although one or more of the parts specified in the letters patent may be used in combination by the defendant. The plaintiffs, by their specification and summing up, treated the parts described as essential parts of their combination, for the purpose of brace and draught, and the use of either alone by the defendant would not be an infringement of the combination patented. It was held that the instructions of the Circuit Court were correct. [Prouty v. Ruggles, 16 Peters, 333.

11. It is not a defence that the plaintiff was not himself the original projector of the improvement, if the patent was taken out with the knowledge and assent of the original projector, and not in fraud of his right. [Dixon v. Moyer, 4 Wash. C. C. R., 68.

12. The plaintiff must in all cases prove an infringement of his right subsequent to the date of his application, or patent; but if the defendant attempts to avoid the patent, by showing that the plaintiff was not the original discoverer, the patent will be considered as relating back to the original discovery. [Ibid.

13. It lies on the defendant to show that some other person than the patentee was the original inventor: it is the point of his defence, and he must substantiate it. [Ibid.

14. The act of January 21, 1808, ch. 117, for the relief of Oliver Evans, does not authorize those who erected his machinery, between the expiration of his old patent and the issuing of the new one, to use it after the issuing of the latter. Jordan et al., 9 Cranch, 199.

[Evans v.

15. If the patent is broader than the invention, or if it is not sufficiently descriptive, taken in connection with the specification, the plaintiff cannot recover in an action for its violation. If however, the patent is too broad, in its general terms, it may be limited by a surrender and a disclaimer, if they show the thing intended to be patented, and that no claim is made to anything

before known or used. [Whitney v. Emmett, 1 Bald., 308.

16. In an action in the Circuit Court of the United States, for the violation of a patent, the court cannot give judgment, declaring the patent void, only in the cases provided for in the 6th section of the act of 1793. If the patent is defective for any other cause, the court can only render judgment generally for the defendant. [Ibid.

17. A patent right is infringed by making the thing patented, though employed by another to do so. [Boyce v. Dorr, 3 M'Lean, 582.

18. But where the thing was made without the knowledge of its having been patented, more than nominal damages should not be given. [Ibid.

19. An assignee of an exclusive right to use machines within a particular district, can maintain an action for an infringement of the patent within that district, even against the patentee. [Stimpson v. Westchester R. R. Co., 4 Howard, 380.

20. Under the act of Congress of January 21, 1808, ch. 117, and a patent taken out pursuant to it, Oliver Evans might recover damages for the use of a machine violating his patent, after notice of the patent, although the machine might have been constructed prior to the passing of the act. [Evans v. Weiss, 2 Wash. C. C. R., 342; 3 Hall's Am. Law Journ., 108, S. C.

21. Under the general patent law, the plaintiff has a right to recover against a person who erected

a machine prior to the issuing of a patent, and made use of it afterward. [Ibid.

22. The patent is for a combination, and the improvement consists in arranging different portions of the plough, and combining them together in the manner stated in the specification, for the purpose of producing a certain effect. None of the parts referred to are new, and none are claimed as new; nor is any portion of the combination less than the whole claimed as new, or stated to produce any given result. The end in view is proposed to be accomplished by the union of all, arranged and combined together in the manner described; and this combination, composed of all the parts mentioned in the specification, and arranged with reference to each other, and to other parts of the plough, in the manner therein described, is stated to be the improvement, and is the thing patented. The use of any two of these parts only, or of two combined with a third, which is substantially different in the form, or in the manner of its arrangement and connection with the others, is, therefore, not the thing patented. It is not the same combination if it substantially differs from it in any of its parts. [Prouty v. Ruggles, 16 Peters, 336.

23. A mere workman, employed by a person, who is not the patentee, to make parts of a patented machine, is not liable to a penalty under the statute of the 21st of February, 1793. [Delano v. Scott, Gilpin, 489.