nature of the latter and its characteristic differences from the former could be ascertained.8

§ 503. The Description: its Sufficiency a Question of Fact.

The sufficiency of the Description is a question of fact, to be investigated by experience, elucidated by evidence, and decided by a jury. Only persons skilled in the art are usually capable of judging whether its delineations are correct, complete, and intelligible, and whether from it alone they could construct and use the invention. The inventor, having adopted it as his method of communicating his discovery to the public as represented by such persons, is bound by it and must abide the result of their endeavors to make the art or instrument available for practical use by following the directions he has given. But where a Description is, upon

produce the given effect, see Gottfried v. Phillip Best Brewing Co. (1879), 17 O. G. 675; 5 Bann. & A. 4.

That an application for an improvement must distinguish it from the original but need not disclaim the original, see Ex parte Firm (1887), 39 O. G. 1199.

3 That the specification for an improvement must describe its nature and extent, and it is not sufficient that by comparing the old and the improved machines the difference might be detected, see Evans v. Eaton (1822), 7 Wheat. 356; 1 Robb, 336; Foxwell v. Bostock (1864), 10 L. T. Rep. N. s. 144.

§ 503. 1 In Forbes v. Barstow Stove Co. (1864), 2 Clifford, 379, Clifford, J.: (392) "The specifications are required for two principal purposes: first to inform the public what the thing is of which the patentee claims to be the inventor; and, secondly, to enable the public, after the expiration of the patent, to practise the invention from the specification, as therein described. Whether the patentee has described the subject-matter, or what he claims to have invented, so as to enable the public to know what his claim is, is in gen

eral a question of law for the court on the construction of the patent. Cur. on P. § 130, p. 130. But whether he has described the invention in such full, clear, and exact terms as to enable the public to practise it from the specification is in general a question of fact to be determined, in common-law cases, by a jury. The act of Congress does not require the patentee to address himself to the uninformed upon the particular subject, but allows him to speak to persons of competent skill in the art; and it only requires him to use such full, clear, and exact terms, as will enable that class of persons to reproduce the thing described from the description given in the specification."

See also Page v. Ferry (1857), 1 Fisher, 298; Reutgen v. Kanowrs (1804), 1 Wash. 168; 1 Robb, 1; Morton v. Middleton (1863), 1 Cr. S. 3d Series, 721; Wallington v. Dale (1852), 7 Exch. 888; Beard v. Egerton (1848), 19 L. J. C. P. 38; Walton v. Bateman (1842), 1 Web. 613; Neilson v. Harford (1841), 1 Web. 295; Bickford v. Skewes (1839), 1 Web. 214; Hill v. Thompson (1817), 1 Web. 235; 1 Abb. P. C. 299.

its face, so incomplete or unintelligible as to be evidently useless for purposes of public information, the court may decline to hear the testimony of witnesses and on its own judgment declare the patent void.2

SECTION VI.

OF THE APPLICATION: THE CLAIM.

§ 504. The Claim: its Objects and General Requisites.

It is the office of the Claim to define the limits of that exclusive use which is secured to the inventor by the patent, and thus to draw the line between those arts or instruments that are open to the public, and those whose employment by it is forbidden until the patent has expired. The Claim is, therefore, an essential part of the specification; and without it one of the two great purposes of that instrument would remain unfulfilled. Hence the statutes require not only that the inventor shall fully describe his invention in the specification, so that any person skilled in the art can practise it, but also that he shall "particularly point out and distinctly claim the part, improvement, or combination which he claims as his invention or discovery." And the rules of the Patent Office prescribe that the specification shall conclude with a specific and distinct Claim or Claims of every separate sub

2 In Wood v. Underhill (1847), 5 How. 1, Taney, C. J.: (4) "In patents for machines the sufficiency of the Description must, in general, be a question of fact to be determined by the jury. And this must also be the case in compositions of matter where any of the ingredients mentioned in the specification do not always possess exactly the same properties in the same degree. But when the specification of a new composition of matter gives only the names of the substances which are to be mixed together, without stating any relative proportion, undoubtedly it would be the duty of the court to de

clare the patent to be void. And the same rule would prevail where it was apparent that the proportions were stated ambiguously and vaguely." 2 Robb, 588 (593).

See also Brooks v. Jenkins (1844), 3 McLean, 432.

§ 504. That where there is no Claim there is no application, see Ex parte Lasscell (1884), 28 O. G. 1274; 29 O. G. 861; Ex parte Holt (1884), 29 O. G. 171.

That a thing is not claimed when shown only in the drawings and not in the Description or Claim, see Couse v. Johnson (1879), 16 O. G. 719.

ject-matter that the applicant desires to protect by the patent for which he has applied.2

§ 505. The Claim the Life of the Patent and the Measure of the Patent Privilege.

The Claim is thus the life of the patent so far as the rights of the inventor are concerned, and by it the letters-patent, as a grant of an exclusive privilege, must stand or fall. The 2 That each Claim is an independent See also Keystone Bridge Co. v. Phœnix patent, see Celluloid Mfg. Co. v. Zylo- Iron Co., 95 id. 274, 278. In view, nite Brush & Comb Co. (1886), 27 Fed. therefore, of the statute, the practice Rep. 291; 35 O. G. 1228; United of the Patent Office, and the decisions Nickel Co. v. California Electrical Works of this court, we think that the scope (1885), 25 Fed. Rep. 475; 11 Sawyer, of letters-patent should be limited to 250. the invention covered by the Claim, and that though the Claim may be illustrated, it cannot be enlarged by the language used in other parts of the specification." 20 O. G. 1891 (1892).

§ 505. In Railroad Co. v. Mellon (1881), 104 U. S. 112, Woods, J.: (117) "The act of July 4, 1836, c. 357 (5 Stat. 117), under which this patent was issued, requires that an applicant for a patent shall not only 'deliver a written description of his invention or discovery,' but 'shall also particularly specify and point out the part, improvement, or combination which he claims as his own invention or discovery.' This provision is substantially re-enacted in the act of July 8, 1870, c. 230 (16 Stat. 198), Rev. Stat. sect. 4888, and remains in force. As a rule, therefore, the specification filed with the application for letters-patent contains a general Description of the invention sought to be patented, which is followed by what is technically called the 'Claim.' In reference to this latter part of the specification this court, speaking by Mr. Justice Bradley, has said: 'It is well known that the terms of the Claim in letters-patent are carefully scrutinized in the Patent Office. Over this part of the specification the chief contest generally arises. It defines what the Office, after a full examination of previous inventions and the state of the art, determines the applicant is entitled to.' Burns v. Meyer, 100 U. S. 671.

In Masury v. Anderson (1873), 11 Blatch. 162, Blatchford, J.: (165) "The rights of the plaintiff depend upon the Claim in his patent, according to its proper construction, and not upon what he may erroneously suppose it covers. If at one time he insists on too much, and at another on too little, he does not thereby work any prejudice to the rights actually secured to him." 6 Fisher, 457 (460); 4 O. G. 55 (56).

In Pitts v. Wemple (1855), 1 Bissell, 87, Drummond, J.: (90) "The Patent Law requires the inventor to set forth the nature and extent of his discovery, so that, by referring to his letters-patent, a mechanic of competent skill may be able, in the state of the art as then understood, to construct the machine or improvement, if the invention relate to a machine. And he must particularly specify and point out the part, improvement, or combina tion which he claims as his own invention or discovery. He is restricted to this Claim. It is true that the whole patent, including specifications and drawings, is to be taken into considera

thing patented is the thing claimed, whatever the patentee may suppose or assert that he has invented; and though the statement of the Claim comes short of the true limits of the invention, the inventor must abide by them, as he has described and published them in this written definition of its character and scope. The courts will not go into the history of the art

to ascertain what he has really discovered and what he might have patented if he had chosen, but will take him at his word. and protect him according to the terms in which he has himself demanded such protection. Even where he confines the language of his Claim to a mere reference to the letters affixed to the drawings, the rigidity of the rule is not relaxed, and only the devices shown in the drawings thus referred to are regarded as constituting his invention.1

§ 505