such amendment is proper. General Electric v. Cooper Hewitt 249 Fed. 61 (64). This case also reaffirms the rule that "insertions by way of amendment do not hurt the patent if they are only amplifications and explanations of what was already reasonably indicated to be within the invention-something which might be fairly deduced from the original application". See also Cleveland v. Detroit 131 Fed. 853.

The question of admitting or refusing amendments to a pending case is left largely to the discretion of the Office, and numerous court decisions refer to the "strict Office rule against new matter".

Amended Theory of Operation.

An inventor is not required to understand or to state any theory of explanation of the scientific principles underlying his invention. It is only necessary that he make such disclosures that his invention can be used. Diamond v. Consolidated 166 O. G. 251. Even a mistaken theory will not ordinarily invalidate a patent. Hemolin v. Harvey 138 Fed. 54. A newly discovered theory which was inherent in the structure and does not involve a distinct or inconsistent invention may be added by amendment. Cleveland v. Detroit, supra. But if the amendment is made without a supporting oath and adds a different theory which is speculative or highly doubtful, or which leaves the terms of the disclosure not sufficiently precise, and especially if made to avoid the prior art, claims based thereon are invalid. Stewart v. American Lava 1909 C. D. 557. If the new theory of operation requires a change in the disclosure of structure, and would operate to appropriate the invention of another, such amendment is not permissible. Davis v. Morgan 306 O. G. 3.

Newly Discovered Uses.

An inventor is entitled to protection on all the uses to which his invention may be put, whether he is aware of

them at the time of filing his application. Miller v. Eagle 66 O. G. 845; Minneapolis v. Barnett 257 Fed. 302. But if a new and obvious use is evolved which itself amounts to a separate invention or patentable discovery, it can not be added by amendment to the application or be protected by the original patent. Thus, a process not disclosed in an apparatus patent but which it is later discovered can be carried out by that apparatus, is a distinct invention. American Sewerage v. Pawtucket 146 Fed. 753 (756).

In those cases in which use goes to the essence of the invention, the addition of newly discovered uses should be allowed with caution. The disclosure of such uses in the patent would be desirable as a dedication to the public of the unclaimed uses, and might be justified as a privilege extended to the patentee to forestall subsequent "use" patents which might be sought by others and thereby limit his patent. However later attempts to file divisional or reissue applications for these newly discovered uses added to the original specification by amendment would raise the question of new matter. Upon principle it would seem that such amendments should be refused, but practical considerations may dictate otherwise.

Inherent Functions.

We have seen that a function inherent in but not disclosed in an element of a patent is available as an anticipation. Scofield v. Rodman 321 O. G. 226. Also claims may be based on a function inherent in but not originally disclosed in a specification. Ellis v. Shaw 321 O. G. 223. It follows that a disclosure can be added by amendment based upon a function which is inherent in an element of the original disclosure, provided that the recognition of the fact that this function is inherent does not amount to a distinct invention. American Cone v. Denaro 334 O. G. 3.

(To be continued.)

EXTENSION OF PATENTS

By C. H. LANE.

The following information relating to the extension of patents granted since the law of 1861 was enacted were brought to light in a recent investigation.

Legislative History.

The patent act of 1790 provided under certain conditions that patents for inventions might be granted for a term not to exceed fourteen years.

The act of July 4, 1836 provided for patent extensions, usually for seven years additional.

Section 16, Act of March 2, 1861 made the term of patents seventeen years and prohibited extensions of patents granted after that date. The last extension under the act of 1836 was in 1875 and expired in 1882.

Patents may be extended by Act of Congress at any time and the power was exercised as far back as 1808. These extensions were also usually for seven years.

Statute.

Sec. 4884 and a grant to the patentee, his heirs or assigns, for the term of seventeen years the right to make use and vend the invention or discovery.

Rule.

Rule 180-Patents cannot be extended except by act of Congress.

Explanation of Tables.

After March 2, 1875, when all patents granted under the Act of 1836 expired, no extension could be granted as a matter of right. The only exception to the rule requiring an act of Congress was in the case of the patent to Gibson, 29,126, Table III, below, where the Commissioner, in January, 1878, extended the patent seven years from its expiration in 1874. The record of this case shows that on June 27, 1874, the then Commissioner of Patents had

decided that an extension ought to be granted, and therefore the Commissioner simply performed the act which his predecessor declared should be performed.

For more than two years after March 2, 1875, Congress occasionally authorized the Commissioner to extend expired patents which had been granted under the Act of 1836. Lists of such patents and data pertaining thereto are given in the annexed Tables I and III. In Table I there is a long lapse between the expiration of the respective patents and the beginning of the sevenyears extension. In Table III the extensions are antedated so as to begin at the expiration of the respective patents, which expiration of course, was before March 2, 1875.

The only mechanical patent granted since March 2, 1861, (for seventeen years) which has been extended is the patent to Henrietta Cole, 55,469, June 12, 1866. Two design patents granted since March 2, 1861, have been extended. Both designs were for badges of patriotic societies. These three patents are listed in Table II.

Table IV shows several miscellaneous special acts of Congress relating to patents and applications for patents.

Table I.

MECHANICAL PATENTS GRANTED FOR FOURTEEN YEARS UNDER ACT OF 1836-EXTENDED SINCE MARCH 2, 1875 UNDER SPECIAL ACTS OF CONGRESS.

FOR TERMS OF SEVEN YEARS BEGINNING LONG AFTER EXPIRATION OF PATENTS.

John Haseltine, 14,535, March 25, 1856, for Water Wheels, Extended seven years from February 18, 1875, by authority of Act of Congress, approved February 18, 1875, Granted October 14, 1875. Harvey Lull, 10,477, January 31, 1854, antedated Jan. 2, 1854 for Shutter Hinges, Extended seven years from July 26, 1876, by authority of Act of Congress, approved April 29, 1876. Granted July 29, 1876.

John R. Harrington, 14,585, April 1, 1856, reissued Dec. 11, 1866, (2415 and 2416), for Machines for Making Carpet Lining. Extended seven years from August 14, 1876, by authority of Act of Congress, approved August 14, 1876. Granted November 15, 1876. John R. Harrington, 14,585, April 1, 1856, reissued Dec. 11, 1866, (2415 and 2416), for Carpet Linings. Extended seven years from August 14, 1876, by authority of Act of Congress, approved August 14, 1876. Granted November 15, 1876.

Henry Voelter, 21,161, August 10, 1856, antedated August 29, 1856, for Reducing Wood to Paper Pulp. Extended seven years from Aug. 29, 1870. Reissued June 6, 1871, No. 4418, and June 13, 1877.

Extended seven years from Aug. 29, 1877, by authority of Act of Congress, approved March 3, 1877. Granted August 24, 1877.

Erastus S. Bussell, 10,280, November 29, 1853, for India Rubber and Steel Springs.

Extended seven years from Nov. 29, 1867. Reissued December 13, 1870, No. 4202. Extended seven years from Oct. 6, 1877, by authority of Act of Congress, approved March 3, 1877. Granted October 6, 1877.

Table II.

PATENTS GRANTED SINCE MARCH 2, 1861-EXTENDED BY VIRTUE OF SPECIAL ACTS OF CONGRESS.

MECHANICAL PATENTS.

Henrietta Cole, 55,469, June 12, 1866, for Fluting Machines, Reissued April 25, 1871, No. 4349, and June 30, 1887.

Extended seven years from June 12, 1883, by authority of Act of Congress, approved August 4, 1886, Granted August 29, 1887.

DESIGN PATENTS.

George Brown Good, Assignor to National Society D. A. R. 21,053, September 22, 1891, Design for Badge.