and Transmitting Evidence," &c., marked XXVI., page 99. The documents and testimony must be filed in the Patent Office on or before the day appointed by the Commissioner for a hearing. The Commissioner may, however, at his discretion, adjourn the heariug to suit the convenience of parties. 4. When the interference arises between an ap-. plication and a patent already issued, the office has no power over the patent, though it decides in favour of the other party; but recource may be had in law for infringement. A reasonable time is always allowed by the Commissioner, in which for the unsuccessful applicant to appeal, should he desire to do so.

XXIII. Caveats.

1. "Any citizen of the United States, or alien who shall have been a resident of the United States one year next preceding, and shall have made oath of his intention to become a citizen thereof, who shall have invented any new art, machine, or improvement thereof, and shall desire farther time to mature the same, may, on paying to the credit of the Treasury, in manner as provided in the ninth section of this act, the sum of twenty dollars, file in the Patent Office a caveat, setting forth the design and purpose thereof, and its principal and distinguishing characteristics, and praying protection of his right, till he shall have matured his invention; which sum of twenty dollars, in case the person filing such caveat shall

afterward take out a patent for the invention therein mentioned, shall be considered a part of the sum herein required for the same. And such caveat shall be filed in the confidential archives of the office, and preserved in secrecy. And if application shall be made by any other person, within one year from the time of filing such caveat, for a patent of any invention with which it may in any respect interfere, it shall be the duty of the Commissioner to deposit the description, specifications, drawings, and model in the confidential archives of the office, and give notice (by mail) to the person filing the caveat of such application, who shall, within three months after receiving the notice, if he would avail himself of the benefit of his caveat, file his description, specification, drawings, and model; and if, in the opinion of the Commissioner, the specifications of claim interfere with each other, [as stated in XXII., page 90,] like proceedings may be had in all respects as are in this act provided in the case of interfering applications." [Sect. 7, act July, 1836.

2. The caveat "should describe something more than the mere effect to be produced. It is quite common to receive one which merely claims the accomplishment of some object, without explaining the means to be employed. This is not enough. It should also disclose the mode of effecting the object, so far, at least, as it has been matured in the inventor's mind." And it would be well, where practicable, to accompany it with a

model and drawings, though these are not indispensable. "As fast as the inventor makes any progress in maturing his contrivance, and adopts means for securing its successful operation, he may file additional papers describing them, which will be kept with the original caveat;" but they must relate to the subject of the caveat only.

3. It should be observed, that "the year is reckoned from the time the caveat is made complete, and the fee paid, and not from the time of filing any additional papers."

4. The papers "filed upon a caveat cannot be withdrawn or altered; neither are they open to the inspection of the caveator himself, except in the presence of a sworn officer. He may have copies of them, as may others who have his permission in writing. Without such permission, no information respecting them will be furnished to strangers, except to a limited extent in certain controversies which may arise respecting them.” [Rules of Patent Office.

XXIV. Form of Caveat.

1. "To the Commissioner of Patents:

66

"The petition of John Fitch, of Philadelphia, in the county of Philadelphia, and state of Pennsylvania

Respectfully represents,

"That he has made certain improvements

in the mode of constructing the boilers of steam engines, and that he is now engaged in making

experiments for the purpose of perfecting the same, preparatory to his applying for letters patent therefor. He therefore prays that the subjoined description of his invention may be filed as a caveat in the confidential archives of the Patent Office, agreeably to the provisions of the act of Congress in that case made and provided, he having paid twenty dollars into the Treasury of the United States, and otherwise complied with the requirements of the said act.

(Signed)

"JOHN FITCH."

2. Note.-Here should follow a description of the general principles of the invention, as far as it has been completed, according to XXIII., 2, page 92.

XXV. Patent Extensions.

1. "Whenever any patentee of an invention or discovery shall desire an extension of his patent beyond the term of its limitation, he may make application therefor, in writing, to the Commissioner of the Patent Office, setting forth the grounds thereof; and the Commissioner shall, on the applicant's paying the sum of forty dollars to the credit of the treasury, as in the case of an original application for a patent, cause to be published in one or more of the principal newspapers in the City of Washington, and in such other paper or papers as he may deem proper, and published in the section of country most interested adversely to the extension of the patent, a notice of such ap

plication, and of the time and place when and where the same will be considered, that any person may appear and show cause why the extension should not be granted. And the Commissioner of Patents shall constitute a board to hear and decide upon the evidence produced before him, both for and against the extension, and shall sit for that purpose at the time and place designated in the published notice thereof. The patentee shall furnish to the Commissioner of Patents a statement in writing, under oath, of the ascertained value of the invention, and of his receipts and expenditures, sufficiently in detail to exhibit a true and faithful account of loss and profit in any manner accruing to him from and by reason of said invention. And if, upon a hearing of the matter, it shall appear to the full and entire satisfaction of the Commissioner, having due regard to the public interest therein, that it is just and proper that the term of the patent should be extended, by reason of the patentee, without neglect or fault on his part, having failed to obtain, from the use and sale of his invention, a reasonable remuneration for the time, ingenuity, and expense bestowed upon the same, and the introduction thereof into use, it shall be the duty of the Commissioner to renew and extend the patent, by making a certificate thereon of such extension, for the term of seven years from and after the expiration of the first term; which certificate of the Commissioner shall be entered on record in the Patent Office; and