vided he has made application therefor, "the right of applying for and obtaining such patent shall devolve on the administrator or executor of such person, in trust for the heirs at law of the deceased, if he shall have died intestate; but if otherwise, then in trust for his devisees, in as full and ample manner, and under the same conditions, limitations, and restrictions, as the same was held, or might have been claimed or enjoyed, by such person in his or her lifetime; and when application for a patent shall be made by such legal representatives, the oath or affirmation shall be so varied as to be applicable to them." [Sect. 10, act 1836.

10. All patentees, and assignees of Patents, are required to stamp, engrave, or impress the article or articles patented and vended, with the date of the patent, under a penalty of one hundred dollars, and the cost of suit instituted for the recovery thereof. [Sect. 6, act 1842.

II. Application for a Patent.

1. No application can be entertained or examined until the fees for the patent are paid, and the specification, model, and drawings are filed in the Patent Office.

2. Application for a patent must be made to the Commissioner in writing, [in the form of petition annexed,] which application or petition should be signed by the inventor, even in case of assignment or otherwise:

III. Form of Petition for a Patent.

"To the Commissioner of Patents,

"Washington City, D. C.:

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

"Respectfully represents :

"That your petitioner has invented a new [and improved mode of propelling vessels by steam] which he verily believes has not been known or used prior to the invention thereof by your petitioner. He therefore prays that letters patent of the United States may be granted to him therefor, vesting in him and his legal representatives the exclusive right to the same, upon the terms and conditions expressed in the act of Congress in that case made and provided; your petitioner having paid thirty dollars into the Treasury, and complied with other provisions of the said act. "JOHN FITCH."

IV. Specification.

1. "Before any inventor shall receive a patent for any such new invention or discovery, he shall deliver a written description of his invention or discovery, and of the manner and process of making, constructing, using, and compounding the same, in such full, clear, and exact terms, avoiding unnecessary prolixity, as to enable any person skilled in the art or science to which it appertains, or with which it is most nearly connected, to

make, construct, compound, and use the same; and in case of any machine, he shall fully explain the principle, and the several modes in which he has contemplated the application of that principle or character by which it may be distinguished from other inventions; and shall particularly specify and point out the part, improvement, or combination, which he claims as his own invention or discovery." [Act 1836, clause sect. 6. See "Form of Specification" annexed, marked V.]

2. It is desirable in all cases to have the specification describe the sections of the drawings, and refer by letters (a, b, c, d, &c.) to the parts respectively. Duplicate drawings are also required.

3. A defective specification or drawing may be amended at any time before a patent has issued, in which case the applicant will be required to make oath anew. If papers be withdrawn from the Patent Office with a view to their alteration, amendment, or modification, the reapplication will take its turn as if it were an original case, and date from the day on which the said papers, as amended or modified, are again placed on the files of the office.

V. Form of Specification.

1. "To all whom it may concern:

"Be it known that I, John Fitch, of Philadelphia, in the county of Philadelphia, and state of Pennsylvania, have invented a new and improved mode of preventing steam-boilers from bursting;

and I do hereby declare that the following is a full and exact description, to wit:

"The nature of my invention consists in providing the upper part of a steam-boiler with an aperture, in addition to that for the safety-valve; which aperture is to be closed by a plug, or disc of alloy, which will fuse at any given degree of heat, and permit the steam to escape, should the safetyvalve refuse to perform its functions.

"To enable others skilled in the art to make and use my invention, I will proceed to describe its construction and operation. I construct my steam-boiler in any of the known forms, and apply thereto guage-cocks, a safety-valve, and the other appendages of such boilers; but, in order to obviate the danger arising from the adhesion of the safety-valve, and from other causes, I make a second opening in the top of the boiler, similar to that made for the safety-valve, as shown at A in the accompanying drawing; and in this opening I insert a plug (a) or disc of fusible alloy, securing it in its place by a metal ring, or screws, or otherwise. This fusible metal I in general compose of a mixture of lead, tin, and bismuth, in such proportions as will ensure its melting at a given temperature, which must, be that to which it is intended to limit the steam, and will, of course, vary with the pressure the boiler is intended to sustain. I surround the opening containing the fusible alloy by a tube B, intended to conduct off any steam which may be discharged therefrom. When

the temperature of the steam, in such a boiler, rises to its assigned limit, the fusible alloy will melt, and allow the steam to escape freely, thereby securing it from all danger of explosion.

“What I claim as my invention, and desire to secure by letters patent, is the application to steamboilers of a fusible alloy, which will melt at a given temperature, and allow the steam to escape, as herein before described-using for that purpose any metallic compound which will produce the intended effect.

"Witness

John Doe,

Richard Roe."

"JOHN FITCH.

[Form adopted by Commissioner of Patents, 1849.]

The signatures of two witnesses are required by clause of sect. 6, act of July, 1836.

Or, should the application be for a machine, the specification should read as follows:

2. "Be it known that I, John Fitch, of Philadelphia, in the county of Philadelphia, and state of Pennsylvania, have invented a new and useful machine for;" and then annex a full description thereof, as in the preceding example.

Or, should the application be for an improvement on something already patented and introduced to the public, the specification should read thus:

3. "Be it known that I, John Fitch, of Philadelphia, in the county of Philadelphia, and state of