latter was obtained surreptitiously, or upon false suggestions. [Ibid.

29. The sixth section of the patent act does not enumerate all the defences of which the defendant may legally avail himself; he may give in evidence that he never did the act attributed to him; that the patentee is an alien, not entitled under the act; or that he has a license or authority from the patentee. [Whittemore v. Cutter, 1 Gallis, 476.

30. Where a bill in equity was brought for an injunction against the defendants, to restrain them from using and selling a planing machine, constructed according to the specification in the plaintiff's patent, it was held that, after the lapse of time which had occurred since the patent was granted, taken together with other circumstances of the case, the affidavit of a single witness was not sufficient to outweigh the oath of the patentee, and the general presumption arising from the grant of the letters patent. [Woodworth v. Sherman, 3 Story, 171.

31. In an action for an infringement of a patent right, evidence that the invention of the defendant is better than that of the plaintiff, is improper, except to show a substantial difference between the two inventions. [Alden v. Dewey, 1 Story, 336.

32. Where the defendant offered evidence to show that the invention was not original with the plaintiff, but that the improvement for which he had taken out letters patent had been suggested to him, although the precise mode of carrying it

into operation had not been suggested, the court instructed the jury that the true question was, whether the improvement was substantially communicated to the plaintiff, so that, without more inventive power, he could, or could not, have applied it. [Ibid.

33. In considering the question of the originality of an invention, the oath of the inventor, made prior to the issue of the letters patent, that he was the true and first inventor of the improvement, may be opposed to the oath of a witness in the case, whose testimony is offered to show that the invention was not original. [Ibid.

34. It is a presumption of law that, when a patent has been obtained, and specifications and drawings are recorded in the Patent Office, every person who subsequently takes out a patent for a similar machine has a knowledge of the preceding patent. [Odiorne v. Winkley, 2 Gallis, 51.

35. The first inventor who has put the invention in practice, and only he, is entitled to a patent. [Kneass v. The Schuylkill Bank, 4 Wash. C. C. R., 9, 106.

36. Every subsequent patentee to him who first puts his invention in practice, although an original inventor, may be defeated of his patent right upon proof of such prior invention being put into use. [Ibid.

37. Objections that a patented invention is old; or that the specification in a patent does not clearly describe the mode of making the machine;

or that the original and the renewed patents are not for the same invention; or that either was obtained with a fraudulent intent, all involve matters of fact, and are for the jury, upon the evidence adduced, to decide. [Carver v. Braintree Manuf. Co., 2 Story, 432.

38. There is no limitation to the period in which the defendant, under the general issue, may give in evidence that the patentee was not the original inventor. [Evans v. Eaton, 1 Peters, C. C. R.,

322.

39. Where the evidence is offered to prove that the "acting commissioner," who signs a patent, was not appointed by the President, it is questionable whether it be competent to admit it in controversies where he is not a party. [Woodworth v. Hall, 1 Woodbury, 389.

40. Under the patent law of 1836, the chief clerk is held to be the "acting commissioner," as well in the necessary absence of the head of the office, as in case of a vacancy de jure. [Ibid.

41. Under a notice that the defendant will prove the prior use of the machine in the United States, he will not be permitted to give evidence of a prior use in England. [Dixon v. Moyer, 4 Wash. C. C. R., 68.

42. A signature to the patent, and a certificate of copies, by a person calling himself "acting commissioner," is sufficient on its face in controversies between the patentee and third persons, as the

law recognizes an acting commissioner to be lawful. [Woodworth v. Hall, 1 Woodbury, 248.

43. Where Congress granted an extension of the term to an administrator, it was held to be legal, and that the letters of administration need not be produced after such a grant. [Ibid.

44. Where witnesses differ as to the fact of an infringement, an issue should be directed, or an action at law be commenced. [Brooks & Morris

v. Jenkins et al., 3 M'Lean, 250.

45. It is doubtful whether a mere change in the mode of fastening knives on a cylinder, to be ground, or to fasten one, instead of several, is a change in structure from an old machine, suf! ficient to justify a patent for it. [Hovery v. Stevens, 1 Woodbury, 290.

46. If the respondent constructed and used his machine before the complainant took out a patent for his, it is not a justification if he had seen and copied an improvement from the complainant's. [Ibid.

47. Declarations of a party, made before dispute arose, in connection with acts, may be competent evidence for him, as tending to show what intentions then existed. [Ibid.

VI. Surrender and Re-issue of Letters Patent.

1. One who has patented his invention cannot take out a new patent for the same invention, until the first is surrendered, repealed, or declared void. [Morris v. Huntingdon, 1 Paine, 348.

2. The obstacle of an invalid patent may be removed by having it declared void, after a verdict against it, or by having a vacatur entered ex parte in the Department of State, on a surrender of the patent. But the provisions of the sixth section of the act do not enable a patentee to declare his own patent void; and a verdict in a suit on a second patent, in favour of such patent, does not avoid the first patent. [Ibid.

3. It seems, that on surrendering a patent, and taking out a new one, the latter should be only for the unexpired part of the fourteen years since obtaining the first patent. [Ibid.

4. A patent, surrendered and renewed, operates as from the commencement of the original patent, except as to causes of action arising before the renewal. [Woodworth v. Hall, 1 Woodbury, 248.

5. If a mistake occurs in a copy of a patent, it can be corrected without causing any injury; but if it exists in the original patent, it cannot be corrected so as to avail without the assent or resignature of the Secretary of State, [Commissioner of Patents.] [Ibid.

6. But the Commissioner, if correcting it, need not re-sign or re-seal the letters, he being the same officer here who did it before. [Ibid.

7. If the mistake corrected be a material one, the letters cannot operate, except on cases arising after it is made. But if a mere clerical one, quære? [Ibid.

8. Where a renewal of patents surrendered is