A foreign patent granted after the patentee files his American application, but before he obtains his American patent, does not limit the term of the American patent. Mann, 17 O. G. 330.

Where an applicant seeks letters patent for an invention already patented by him abroad, and there is a single well-authenticated instance of a use in public, it constitutes a legal "public" use, and the applica tion will be refused. Hermann v. Gilmore, 1 Dec. Com. 23.

SEC. 4888. Before any inventor or discoverer shall receive a patent for his invention or discovery, he shall make application therefor, in writing, to the commissioner of patents, and shall file in the patent office a written description of the same, and of the manner and process of making, constructing, compounding, and using it, in such full, clear, concise, and exact terms 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 a machine, he shall explain the principle thereof, and the best mode in which he has contemplated applying that principle, so as to distinguish it from other inventions; and he shall particularly point out and distinctly claim the part, improvement, or combination which he claims as his invention or discovery. The specification and claim shall be signed by the inventor and attested by two witnesses.

Statute Revised-July 8, 1870, ch. 230, § 26, 16 Stat. 201.

Prior Statutes-April 10, 1790, ch. 7, § 2, 1 Stat. 110.-February 21, 1798, ch. 11, 1, 1 Stat. 318.--July 4, 1836, ch. 357, 6, 5 Stat. 119.

Character of Proceeding.

The authority of the commissioner to issue grants is not in the nature of jurisdiction in its common and technical acceptation. He issues the grant when he has evidence satisfactory to his own mind that the claimant is entitled to receive it. But that adjudges nothing as to the real right. That question is unaffected, and remains to be examined and decided between parties contesting it without prejudice or advantage from the letters patent. Wilder v. McCormick, 2 Blatch. 31; Potter v. Stevens, 2 Fish. 163; Grant v. Raymond, 6 Pet. 218; s. c. 1 Robb 604.

All the proceedings in the patent office on the subject of patents are ex parte, except in the case of interfering applications. The department

acts rather ministerially than judicially, and upon the representation of the applicant, without entering into an examination of the question of right. Morris v. Huntington, 1 Paine 348; s. c. 1 Robb 448; Potter v. Stevens, 2 Fish. 163.

The commissioner in issuing patents may be considered as a ministerial officer. If the prerequisites of the law are complied with, he can exercise no judgment on the question whether the patent shall be issued. v. Raymond, 6 Pet. 218; s. c. 1 Robb 604.

Clearness.

Grant

It is not necessary that an inventor shall reduce his invention to practical use before the patent is obtained. No such condition is required by the statute. It is enough that the inventor has perfected his invention, and is able to furnish to the patent office such specifications and model as the law requires. Wheeler v. Clipper Co., 6 Fish. 1; s. c. 10 Blatch. 181; 2 O. G. 442.

The requirements of this section are prerequisites to the granting of the patent, and unless the prerequisites are complied with, a party sued for the infringement of a patent may show that they have not been complied with, and in that way defeat the patent. They are conditions precedent to the right of the commissioner to grant a patent. New York v. Ransom, 23 How. 487; s. c. 1 Fish. 252; Seymour v. Osborne, 3 Fish. 555; s. c. 11 Wall. 516; Latta v. Shawk, 1 Fish. 465; s. c. 1 Bond 259; Grant v. Raymond, 6 Pet. 218; s. c. 1 Robb 604.

The specification has two objects: One is to make known the manner of constructing the machine, if the invention is of a machine, so as to enable artisans to make and use it, and thus to give the public the full benefit of the discovery after the expiration of the patent. The other is to put the public in possession of what the party claims as his own invention, so as to ascertain if he claim anything that is in common use, or is already known, and to guard against prejudice or injury from the use of an invention which the party may otherwise innocently suppose not to be patented. Evans v. Eaton, 7 Wheat. 356; s. c. 2 Wash. C. C. 443; s. c. 1 Robb 193, 336; Forbes v. Barstow Stove Co., 2 Cliff. 379; Mabie v. Haskell, 2 Cliff. 507; Conover v. Roach, 4 Fish. 12.

It makes no difference whether the effect is produced by mechanical principles, or by chemical agency, or by the application of discoveries in natural science, as in either case the requirement of the statute is imperative that the patentee must describe the method, process, or means he employs in full, clear, and exact terms, and the end which the invention accomplishes. Mitchell v. Tilghman, 4 Fish. 599; s. c. 19 Wall. 287; 5 O. G. 299; s. c. 9 Blatch. 1; s. c. 2 Fish. 518.

The specification must be perfect of itself, and can not be aided by reference to other matters. Head v. Stevens, 19 Wend. 411.

The law confers an exclusive patent right on the inventor of anything new and useful, as an encouragement and reward for his ingenuity, and for the expense and labor attending the invention. But this monopoly

is granted for a limited term only, at the expiration of which the invention becomes the property of the public. Unless, therefore, such a specification were made as would at all events enable other persons of competent skill to construct similar machines, the advantages to the public which the statute contemplates would be defeated. It is not necessary, however, that the specification should contain an explanation level with the capacities of every person; but it should be expressed in such full, clear, and exact terms, that a person skilled in the art or science of which it is a branch, would be enabled to construct the patented invention. Lowell v. Lewis, 1 Mason 182; s. c. 1 Robb 131; Wintermute v. Redington, 1 Fish. 239; Brooks v. Jenkins, 3 McLean 432; Page v. Ferry, 1 Fish. 298; Seymour v. Osborne, 3 Fish. 555; s. c. 11 Wall. 516; Teese v. Phelps, 1 McAl. 48; Westlake v. Cartter, 6 Fish. 519; s. c. 4 O. G. 636; Lamb v. Hamblen, 11 Fed. Rep. 722; Loom Co. v. Higgins, 105 U. S. 580; s. c. 21 O. G. 2031; 16 O. G. 675; s. c. 15 Blatch. 446; s. c. 4 Ban & Ard. 88; Smith v. Pryor, 2 Saw. 461; s. c. 4 O. G. 633; s. c. 6 Fish. 469; Stillwell & B. Manuf. Co. v. Cin. G. & C. Co., 7 O. G. 829; s. c. 1 Ban & Ard. 610.

The skill and knowledge deemed competent is that which is addressed to the subject-matter, and is not the highest skill or the greatest knowledge, but that of practical workmen of ordinary skill in the particular business. Page v. Ferry, 1 Fish. 298; Smith v. O'Connor, 6 Fish. 469; s. c. 2 Saw. 461; 4 O. G. 633; Mabie v. Haskell, 2 Cliff. 507; Lippincott v. Kelly, 1 West. L. J. 513.

The description need not be so clear as to be understood by an individual wholly unskilled in the structure of machines. Brooks v. Bicknell, 3 McLean 250; s. c. 2 Robb 118; Many v. Sizer, 1 Fish. 17; Mowry v. Whitney, 3 Fish. 157; s. c. 4 Fish. 141; 5 Fish. 496; 14 Wall. 620; 2 Bond 45; Forbes v. Barstow Stove Co., 2 Cliff. 379.

Unless on the mere description of the thing itself, its utility and the manner of its use are obvious, the patentee should always describe the manner of its employment to make it useful, so that a mechanic of proper skill can not only construct the thing itself, but can give it practical application to the purpose for which it is useful. Eddy v. Dennis, 95 U. S. 560; s. c. 4 Fish. 423.

In determining whether the specification is sufficiently full, clear and exact to enable any person skilled in the art to construct the machine, the jury are to look at the models and drawings as well as the specification, and also to the state of the art at the time of the invention. Singer v. Walmsley, 1 Fish. 558; Earle v. Sawyer, 4 Mason 1; s. c. 1 Robb 491; Hogg v. Emerson, 6 How. 437; s. c. 2 Blatch. 1; 11 How. 587; s. c. 2 Robb 655; Burrall v. Jewett, 2 Paige 134.

If from the specification and the drawings taken together, any person skilled in the art could construct and use the device therein described without invention of his own, which would attain the result claimed for it in the patent, then the patent is good, although there may be a mistake in describing the action of some part of the device, but which mistake could

be easily discovered by the mechanic when he came to examine the same. Singer v. Walmsley, 1 Fish. 558.

A patentee has the right to assume that those who desire to understand all the conditions under which the invention can be operated, are acquainted with the preceding state of the art immediately connected with this particular subject. Tompkins v. Gage, 2 Fish. 577; s. c. 5 Blatch. 268.

An intelligent mechanic is chargeable with a knowledge of the state of the art in relation to the subject upon which he is called to exercise his skill. Treadwell v. Parrott, 3 Fish. 124; s. c. 5 Blatch. 369.

The specification need not describe that which is within the ordinary knowledge of any workman who may be employed to put up the apparatus or construct the machine. Such a workman, however, must have a competent knowledge of the work; that is, technically, be what the law calls an expert. Page v. Ferry, 1 Fish. 298; Monce v. Adams, 12 Blatch. 1; s. c. 7 O. G. 177; s. c. 1 Ban & Ard. 126; Pearce v. Mulford, 102 U. S. 112; s. c. 18 O. G. 1223; s. c. 2 Ban & Ard. 190; 13 Blatch. 173; s. c. 9 O. G. 204; Kneass v. Schuylkill Bank, 4 Wash. C. C. 9; s. c. 1 Robb 303. The utmost precision in the description of a machine is not to be expected, nor is it essential. Parts of machinery and processes generally known, need not be described. A wedge, pulleys, rollers, rack and pinion, and other things known to all mechanics, will be supplied by the mechanic without stating their size or structure. Nor is it essential to state the proportionate parts of a machine, nor the velocity of its operation. These are matters of adjustment for the eye and judgment of the constructor. Whether a machine be large in its parts or small, its motion slow or quick, makes no difference in the principle of it. By a detailed description of things generally known, and not essential to the invention, the statement is rendered more prolix and less perspicuous. Brooks v. Jenkins, 3 McLean 432.

Absolute precision as to details is not required in the specification. It is only intended as a guide, but it is not the sole instructor. The special skill of the mechanic, derived from familiarity with the art, may be applied in aid of the instruction given by the specification, and this skill may be exerted to modify any direction in the specification as to the matters of mere adjustment or adaptation of the invention to its intended use. Dorsey Co. v. Marsh, 6 Fish. 387; s. c. 9 Phila. 395.

When the patent is for a new manufacture, the law does not require that all its constituent parts shall be described. The description is sufficient if it enables those who use it and deal in it, to recognize it. Anilin Fabrik v. Higgin, 14 O. G. 414; s. c. 15 Blatch. 219; s. c. 3 Ban & Ard. 462.

The definiteness of a specification must vary with the nature of its subject. Addressed, as it is, to those skilled in the art, it may leave something to their skill in applying the invention, but it must not mislead them. Mowry v. Whitney, 5 Fish. 513; s. c. 14 Wall. 434; 1 O. G. 499. The statute must have a fair and reasonable construction. If the invention can be constructed by the exercise of skill and judgment on the

part of a mechanic, the specification is sufficient. In carrying out any invention, the exercise of some skill and judgment on the part of the mechanic called to construct it, will always be required. Something must necessarily be left to him. If with the exercise of ordinary intelligence and skill, the invention can be constructed from the information given by the patent, the specification answers the requisite of the statute. Judson v. Moore, 1 Fish. 544; s. c. 1 Bond 285; Swift v. Whisen, 3 Fish. 343; s. c. 2 Bond 115; Mowry v. Whitney, 5 Fish. 513; s. c. 14 Wall. 434; 1 O. G. 499.

If a part is omitted which is so common and obvious as to suggest itself to any competent mechanic, this omission will not vitiate the patent. Union Paper Bag Co. v. Nixon, 6 Fish. 402; s. c. 4 O. G. 31; Stillwell & B. Manuf. Co. v. Cincinnati Gas Co., 7 O. G. 829; s. c. 1 Ban & Ard. 610.

It is not essential that the inventor shall be sufficiently learned to thoroughly understand or accurately state, the philosophy of a process which he has invented and reduced to practical use. Cahill v. Beckford, 1 Holmes 48.

If the specification sets forth the thing to be done in such a manner that it can be reproduced, it need not set forth the scientific principle upon which the operation depends. Andrews v. Cross, 19 O. G. 1705; s. c. 19 Blatch. 294; s. c. 8 Fed. Rep. 269.

If eulogiums on the invention are fraudulently inserted to mislead and operate to deceive others in regard to the actual construction of the thing claimed and the mode of applying it to use, they may render the patent void, but where the thing is correctly described, notwithstanding such exaggerations, they are immaterial. Aultman v. Holley, 6 Fish. 534; s. c. 11 Blatch. 317; 5 O. G. 3.

The patentee is not confined to technical words, but should rather employ those in popular use and better understood by all. The fewer technical terms are used the better, if the subject is intelligible without them. Hovey v. Stevens, 3 W. & M. 17; s. c. 2 Robb 567.

The specification must be complete in its description of the invention. No defects can be obviated by extraneous evidence at the trial. Brooks v. Jenkins, 3 McLean 432; Dixon v. Moyer, 4 Wash. C. C. 68; s. c. 1 Robb 324.

If the construction of the machine demands the solution of a problem that requires experiment, the specification is void. Loom Co. v. Higgins, 105 U. S. 580; s. c. 16 O. G. 675; s. c. 15 Blatch. 446; s. c. 4 Ban & Ard. 88.

Where a useful result is produced by the use of certain means for which the inventor or discoverer obtains a patent, the means described must be the essential and absolutely necessary means, and not mere adjuncts which may be used or abandoned at pleasure. Russell v. Dodge, 93 U. S. 460; s. c. 11 O. G. 151.

If the patentee has discovered much and discloses little, he patents no more than he claims. He will not be allowed afterward, when the extent of his right shall be the subject of controversy, either by expanding into