The courts have no power to correct a mistake in letters patent. Their duty is to construe the specification and claim as they stand, and determine the legal effect of the claim. Kittle r. Merriam, 2 Curt. 475.

If enough is left after the rejection of an erroneous description to clearly and certainly identify the mode of constructing the machine, the rule error demonstrationis non nocet applies. Kittle v. Merriam, 2 Curt. 475.

A defect should be clear and palpable to justify a court in saying that a patent is a nullity. It is subject to scrutiny before it passes into the hands of the patentee. The whole claim of the inventor is subjected to an officer who acts under oath, and who is usually a man well skilled in natural philosophy and mechanical science generally, and who would not be justified in granting a patent to any person unless, in his judgment, the specification was sufficiently clear. Judson v. Moore, 1 Fish. 544; s. c. 1 Bond 285.

No court of justice is at liberty to strike out any words which are sensible in the place where they occur, and are capable of a distinct application. Effect is to be given, if practicable, to all the words as containing a distinct expression of the intention of the party. Ames v. Howard, 1 Sum. 482; s. c. 1 Robb 689; Day v. Combination Rubber Co., 17 O. G. 1347; s. c. 5 Ban & Ard. 385; s. c. 2 Fed. Rep. 570.

An error of expression apparent on the face both of the patent and specification, by which no person could be misled, will not invalidate the patent. Kneass v. Schuylkill Bank, 4 Wash. C. C. 9; s. c. 1 Robb 303.

It is the province and duty of the court to settle the meaning of the patent, and if that can not be ascertained satisfactorily upon the face of the specification, the law declares it insufficient for ambiguity and uncertainty. The specification is laid before the jury as defined and settled by the exposition of the court, and the matters of fact presented by the respective parties to support or defeat the patent are then to be examined and applied, as if the construction fixed by the court had been incorporated in the specification. Hogg v. Emerson, 2 Blatch. 1; s. c. 11 How. 587; 6 How. 437; s. c. 2 Robb 655.

Although there is some ambiguity and uncertainty in a part of the specification, yet, if taking the whole together, the court can perceive the exact nature and extent of the claim made by the inventor, it is bound to adopt that interpretation and to give it full effect. Ryan v. Goodwin, 3 Sum. 514; s. c. 1 Robb 725; Swift v. Whisen, 3 Fish. 343; s. c. 2 Bond 115; Middletown Co. v. Judd, 3 Fish. 141.

Whether a claim is vague and uncertain is a question of law to be determined by the rules of construction applied in the light of the state of the art. Blake v. Stafford, 3 Fish. 294; s. c. 6 Blatch. 195.

A description, though in some respects obscure, imperfect, or not so intelligible as to fully answer all the objects of the law, is good if it enables the court to specify the improvement or invention patented from the face of the patent and accompanying papers. It is enough if there is a substantial description of the thing patented, though defective in form or

mode of explanation. Whitney v. Emmett, Bald. 303; s. c. 1 Robb 567 ; Judson v. Moore, 1 Fish. 544; s. c. 1 Bond 285; Wayne v. Holmes, 2 Fish. 20; Blake v. Stafford, 3 Fish. 294; s. c. 6 Blatch. 195.

The patentee is not to be bound down to any precise form of words, and it is sufficient if the court can clearly ascertain by fair interpretation what he intends to claim, and what his language truly imports, even though the expressions are inaccurately or imperfectly drawn. Wyeth v. Stone, 1 Story 273; s. c. 2 Robb 23.

The meaning of letters patent, like other grants or written instruments, must be ascertained by the language employed as applied to the subject-matter. Goodyear Dental Co. v. Gardner, 3 Cliff. 408; s. c. 4 Fish. 224.

Where the language employed is clear and unambiguous, it must speak its own construction in the specification of a patent, as well as in any other grant issued by public authority. 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. Language invoked to support a particular theory must be such as is fit, when it is compared with the whole instrument, to express the imputed intention, else the theory can not be supported. 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.

Particular passages in the description must not be separated from what precedes or follows in the same connection, but one part of the instrument must be compared with another, and the whole considered together, in order to determine whether it is incomplete and ambiguous or sufficient to uphold the claim of the patent. Howes v. Nute, 4 Cliff. 173; s. c. 4 Fish. 263.

Whether a patent claims too much is a question of law to be determined by the rules of construction, applied in the light of the state of the art. Blake r. Stafford, 3 Fish. 294; s. c. 6 Blatch. 195.

If a combination is expressly claimed in one claim by apt and appropriate language, it must be inferred that if it had been intended to claim a combination merely in another claim, appropriate language to indicate such intention would have been used. Burden v. Corning, 2 Fish. 477.

In construing a claim the court can not look to a single phrase only to the exclusion of all the residue of the writing. Kittle v. Merriam, 2 Curt. 475.

The disclaimer at the close of a specification estops the patentee from setting up any privilege to the part disclaimed, and the summary is equally binding on him as a limitation to the thing patented. Whitney v. Emmett, Bald. 303; s. c. 1 Robb 567.

Where mere changes of form become patentable by reason of involving functional differences, the patent should be so construed as to allow subsequent inventors to devise other changes of form involving other functional changes, where the same result is not attained in substantially the same way. Swain T. Manuf. Co. v. Ladd, 11 O. G. 153; s. c. 2 Ban & Ard. 488; s. c. 102 U. S. 409; s. c. 19 O. G. 62.

Similar substance means a substance having the same property, and not a substance having the same chemical constituents. Roots v. Hyndman, 6 Fish. 439; s. c. 4 O. G. 29.

A literal construction is not to be adopted where it would be repugnant to the manifest sense and reason of the instrument. Brown v. Guild, 23 Wall. 181; s. c. 6 O. G. 392; 7 O. G. 739.

The patentee's rights depend on the claim in the 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 time on too little, he does not thereby work any prejudice to the rights actually secured to him. Masury v. Anderson, 6 Fish. 457; s. c. 11 Blatch. 162; 4 O. G. 55.

Although the patentee files a disclaimer of a certain form of the invention in order to obtain a reissue, yet if the patent includes the form as an equivalent, the disclaimer is a mere nullity. Union Metallic Cartridge Co. v. U. S. Cartridge Co., 7 Fed. Rep. 344.

The words of a specification are to be taken together, and they are to be so construed as to give effect to the meaning and intention of the person using them. Words are not to be distorted from their meaning so as to effect what may be supposed to have been the intention of the person using them; but they are to have a reasonable construction as connected with the sentence in which they are used. Allen v. Hunter, 6 McLean 303; Russell Manuf. Co. v. Mallory, 5 Fish. 632; s. c. 10 Blatch. 140; 2 O. G. 495.

It is material to ascertain what was in point of fact the invention, for there is a reasonable presumption that the intention of the inventor was to obtain, and of the Government to concede to him, the exclusive right to what he actually invented. Kittle v. Merriam, 2 Curt. 475.

The construction should not be broader than the whole subject-matter and description and nature of the case indicate as designed. It should not be fancied, but rather what is natural and clear considering what already exists on the subject. Smith v. Downing, 1 Fish. 64; Trader v. Messmore, 7 O. G. 385 ; s. c. 1 Ban & Ard, 639.

There is no artificial or universal rule of interpretation beyond that which common sense furnishes, which is to construe the instrument as a whole, and to extract from the descriptive words and the claim what the invention is which is intended to be patented, and how far it is capable of exact ascertainment, and how far it is maintainable in point of law. Carver v. Braintree Manuf. Co., 2 Story 432; s. c. 2 Robb 141.

An amended specification which is not completed may be considered as an explanation by the patentee of his intended meaning, and can be referred to in considering whether the words, as used in the original specification, carry out clearly or not what is said to have been intended. Hovey v. Stevens, 3 W. & M. 17; s. c. 2 Robb 567.

Where the fair interpretation of the words employed to describe an invention includes matters not in the mind of the patentee at the time, he is as fully authorized to claim the unlooked for as the anticipated result. Welling v. Rubber Co., 7 O. G. 606; s. c. 1 Ban & Ard. 283.

The legal construction of every general claim is that the patentee means to limit the same to his described method or process; or, if it be a machine, to his described means of obtaining or accomplishing the described results. Usually the claim contains the words "as described," or "substantially as described." or words of like import, which are everywhere understood as referring back to the descriptive parts of the specification. Words of such import, if not expressed in the claim, must be implied. 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; Dederick v. Cassell, 20 O. G. 1233; s. c. 9 Fed. Rep. 306.

The words "* substantially as described and shown," relate only to material features of the combination specified, and these are to be ascertained by considering the object or purpose of the machine, and what are the elements of the combination which create its distinctive character, and are effective in producing the peculiar result for which the contrivance is made. Waterbury Brass Co. v. Miller, 15 Fish. 48; s. c. 9 Blatch. 77; Knox v. Murtha, 9 Blatch. 205; s. c. 5 Fish. 174.

The phrase "substantially the same," means the same in all important particulars. Adams v. Edwards, 1 Fish. 1.

On account of the great vagueness and indefiniteness of the language used in describing the various arts, machines, manufactures, and compositions of matter, it is almost impossible to describe the real nature of many discoveries or processes in language free from ambiguity or misconstruction. Different persons looking at it from different points of view, would describe it in different terms. Still, if the patentee has fully set forth his invention, he has done all that the law requires, and is entitled to its protection. The patent should be carefully examined to find the thing discovered; and if it be clearly set forth, the patentee should not suffer for the imperfection or vagueness of the language used in describing its true extent and nature. Goodyear v. Central R. R. Co., 1 Fish. 626; s. c. 2 Wall. Jr. 356.

There are few things more difficult, even for well-educated and practiced lawyers, than to describe a new invention clearly, and point out the principle which distinguishes the subject of it from all things known before. As inventors are rarely experts either in philology or law, it has long been established as a rule that their writings are to be scanned with a good degree of charity. But it is easy to abuse this liberality to the purposes of fraud. The public has rights to be guarded also, and these exact that the patentee's specification shall set forth his invention so fully and definitely that it can not be readily misunderstood. French v. Rodgers, 1 Fish. 133.

A patent for a gold pen can not be extended beyond the peculiar shape, form, or mode of construction which the patentee alleges he has invented. Rapp v. Bard, 1 Fish. 196.

What is the character of the grant made by the patent is a question of law, and must be determined by the court, and the jury must consider that the patent purports to grant that which the court shall determine it

to grant. Serrell v. Collins, 1 Fish. 289; Buck v. Hermance, 1 Blatch. 398; Magic Ruffle Co. v. Douglass, 2 Fish. 330; Union Sugar Refinery v. Matthiessen, 3 Cliff. 639; s. c. 2 Fish. 600; Teese v. Phelps, 1 McAl. 48; Clark Patent Co. v. Copeland, 2 Fish. 221; Case v. Brown, 2 Fish. 268; s. c. 2 Wall. 320; 1 Biss. 382; Waterbury Brass Co. v. N. Y. Brass Co., 3 Fish. 43; Winans v. Denmead, 15 How. 330; s. c. 4 Am. L. J. 498; Conover v. Roach, 4 Fish. 12; Cahoon v. Ring, 1 Fish. 397; s. c. 1 Cliff. 592; Conover v. Rapp, 4 Fish. 57; Foss v. Herbert, 2 Fish. 31; s. c. 1 Biss. 121; Matthews v. Skates, 1 Fish. 602.

The interpretation of the specification is for the court. Experts are examined only to aid in interpreting the language of art, as other translators are. Batten v. Clayton, 2 Whart. Dig. 363.

Trade-Mark.

When a patent expires, the patentee can not claim a trade-mark in the name by which the patented invention was known. Singer Manuf. Co. v. Riley, 11 Fed. Rep. 706; Singer Manuf. Co. v. Stanage, 6 Fed. Rep. 279.

A manufacturer is entitled to be protected in the trade-mark on his articles although he makes them in accordance with a patent that has expired. Singer Manuf. Co. v. Brill, 9 A. L. Rec. 43.

If a machine constructed according to a patent acquires a particular name, a person who manufactures it after the expiration of the patent may call it by that name, but he must put some mark on it to indicate that it was not manufactured by the patentee. Singer Manuf. Co. v. Larsen, 8 Biss. 151; s. c. 3 Ban & Ard. 246.

When the patent expires, a person who has manufactured the thing patented under a trade name has the right to use the trade name as well as to manufacture the thing patented. Filley v. Child, 16 O. G. 261; s. c. 16 Blatch. 376; s. c. 4 Ban & Ard. 353.

Although the patentee used a certain form of a frame which was not covered by the patent, yet he is not entitled to the exclusive use of this after the expiration of the patent. Wilcox & G. S. M. Co. v. Frame, 24 O. G. 1272; s. c. 17 Fed. Rep. 623.

SEC. 4885. Every patent shall bear date as of a day not later than six months from the time at which it was passed and allowed and notice thereof was sent to the applicant or his agent; and if the final fee is not paid. within that period the patent shall be withheld.

Statute Revised-July 8, 1870, ch. 230, § 23, 16 Stat. 201.

Prior Statutes-July 4, 1836, ch. 357, § 8, 5 Stat. 120.-March 3, 1863, ch. 102, § 3, 12 Stat. 796.