ment for plows," is given in his specifications in said patent as follows:

"My invention relates to that class of plow attachments designed as a means of carrying a plowman in such position, relative to a plow, that his weight will aid in making the plow run smoothly and evenly without increasing the draft and labor of the horses, and that he may, by simply adjusting levers at his side, readily govern the width and depth of the furrow, and plow a field uniformly with a common plow without walking."

As to this first patent, counsel for plaintiff, in his printed brief, says (page 3):

"The plow shown in the drawings and described in the specifications is a three-wheeled riding plow, rigid in all its parts, but capable of two adjustments, viz. one for raising or lowering the front end of the plow beam, the other for changing the vertical plane of the plow and plow beam. The claims on which the plaintiff principally relies are the first and third. They are as follows:

"(1) In combination with plow beam and hinged axle, the lever, B, having the combination rack and fender, y, and lever, B', provided with the spring latch, z', substantially as and for the purposes shown and described.'

(3) The vertical lever, B', having the combined rack and fender, y, and the gravitating latch, h, the hinged axle, C, carrying the wheel, D, and rack, g, the jointed fulcrum, t, clamping the coulter, w, x, the horizontal lever, B2, having a spring latch at its rear end, and carrying a caster wheel at its front end, and the adjustable brace, m, when arranged and combined to operate substantially as and for the purposes shown and described.'

"While it is our opinion that the invention of Mr. McBride is fairly set forth in both claims, we prefer the expression found in the first claim, and shall, therefore, while insisting upon both, give our attention chiefly to the first. This claim substantially describes, and claims in combination, all the essential parts of the plow. It omits nothing save the combining mechanism and the three wheels upon which the plow is mounted, and which, as will presently be shown, are not necessary to be specified in the claim, although necessary in the practical operation of the implement. The real discovery made by the complainant was the method of so rigidly attaching a plow beam to the axle upon which the wheels were mounted as that the bottom of the plow would at all times bear a fixed relation to the furrow wheel. This was the characteristic of the invention,-a characteristic that distinguished the plow in which it was embodied from all prior structures; a characteristic that converted failure into success, and revolutionized the industry."

In construing the first claim of this patent (1878), it becomes important to determine whether plaintiff's device is a "primary invention." And this brings us at once to the doctrine to be applied in construing these claims. There can be little difference of opinion as to the basis of this construction.

In Masury v. Anderson, 11 Blatchf. 165, Fed. Cas. No. 9,270, Justice Blatchford said:

"The rights of the plaintiff depend upon the claims in his patent, according to its proper construction, and not upon what he may erroneously suppose it covers.

In Keystone Bridge Co. v. Phoenix Iron Co., 95 U. S. 274, 278, the court say:

"If the patentees have not claimed the whole of their invention, and the omission has been the result of inadvertence, they should have sought to correct the error by a surrender of their patent, and an application for a reissue. * * But the courts have no right to enlarge a patent beyond the scope of its claim as allowed by the patent office or the appellate tribunal to which contested applications are referred. When the terms in a patent

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are clear and distinct (as they always should be), the patentee, in a suit brought upon the patent, is bound by it. He can claim nothing be yond it."

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In White v. Dunbar, 119 U. S. 47, 51, 7 Sup. Ct. 72, the court say: "The claim is a statutory requirement, prescribed for the very purpose of making the patentee define precisely what his invention is; and it is unjust to the public, as well as evasion of the law, to construe it in a manner different from the plain import of its terms."

In McClain v. Ortmayer, 141 U. S. 419, 423, 12 Sup. Ct. 76, the court say:

"While the patentee may have been unfortunate in the language he has chosen to express his actual invention, and may have been entitled to a broader claim, we are not at liberty, without running counter to the entire current of authority in this court, to construe such claims to include more than their language fairly imports. Nothing is better settled in the law of patents than that the patentee may claim the whole or any part of his invention, and that, if he only describe and claim a part, he is presumed to have abandoned the residue to the public. The object of the patent law in requiring the patentee to 'particularly point out and distinctly claim the part, improvement, or combination which he claims as his invention or discovery,' is not only to secure to him all to which he is entitled, but apprise the public of what is open to them. The claim is the measure of his right to relief, and, while the specification may be referred to, to limit the claim, it can never be made available to expand it."

And see Railroad Co. v. Mellon, 104 U. S. 112; Deering v. Harvester Works, 155 U. S. 296, 15 Sup. Ct. 118.

The same principle of construction is clearly and forcibly stated by Circuit Judge Sanborn, in delivering the opinion in Stirrat v. Manufacturing Co., 10 C. C. A. 216, 61 Fed. 980.

"The claim of a specific combination or device in a patent is a renunciation of every claim to any other combinations or devices for performing the same functions that are apparent from the face of the patent, and are not colorable evasions of the combination or device claimed. The statute requires the inventor to 'particularly point out and distinctly claim the part, improvement, or combination which he claims as his discovery.' Rev. St. § 4888. When, under this statute, the inventor has done this, he has thereby disclaimed and dedicated to the public all other improvements and combinations, apparent from the face of his specifications and claims, that are not evasions of the device and combination he claims as his own. The claims of his patent limit his exclusive privileges, and his specific actions may be referred to, to explain and to restrict, but never to expand, them."

The construction of the patent must not be made in an illiberal spirit, with a view to destroy the grant. A patent should be construed in a liberal spirit, to sustain the just claims of the inventor. This principle is not to be carried so far as to exclude what is in it, or to interpolate anything which it does not contain. But liberality, rather than strictness, should prevail where the fate of the patent is involved, and the question to be decided is whether the inventor shall hold or lose the fruits of his genius and his labors. Rubber Co. v. Goodyear, 9 Wall. 788. Patents for inventions are to receive a liberal construction, and, under the fair application of the rule, "ut res magis valeat quam pereat," are, if practicable, to be so interpreted as to uphold, rather than to destroy, the right of the inventor. Turrill v. Railroad Co., 1 Wall. 491.

The further rule is stated by the supreme court in Roemer v. Peddie, 132 U. S. 317, 10 Sup. Ct. 98, that:

"When the patentee, on the rejection of his application, inserts in his specification, in consequence, limitations and restrictions, for the purpose of obtaining his patent, he cannot, after he has obtained it, claim that it shall be construed as it would have been construed if such limitations and restrictions were not contained in it."

Or, as stated in Caster Co. v. Spiegel, 133 U. S. 368, 10 Sup. Ct. 409: "When a patentee has modified his claim in obedience to the requirements of the patent office, he cannot have for it an extended construction which has been rejected by the patent office; and in a suit on his patent his claim must be limited, where it is a combination of parts, to a combination of all the elements which he has included in his claim as necessarily constituting that combination."

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It must be further borne in mind that the state of the art to which an invention belongs, at the time that invention was made, must be considered in construing any claim for that invention. Carlton v. Bokee, 17 Wall. 463; Railway Co. v. Sayles, 97 U. S. 554. "It is well settled that the claim must be read and interpreted with reference to the rejected claims and to the prior state of the art, and cannot be so construed as to cover either what was rejected by the patent office or disclosed by prior devices." Knapp v. Morss, 150 U. S. 225, 14 Sup. Ct. 81.

The file wrapper and contents of plaintiff's 1878 patent are in evidence herein. These show that a patent was not allowed to plaintiff until after the patent office had five times rejected the application, and after plaintiff had five times amended his claim, and that these rejections were almost entirely based on the fact, as determined by that office, that the claims presented by the plaintiff were in conflict with prior patents. Defendants have introduced in evidence over 50 letters patent, prior to the 1878 patent to plaintiff, all of which relate to plow attachments, nearly all to different methods relating to riding plow attachments, and all in some way attempting to produce some of the results claimed herein by plaintiff as resulting from his invention, by devices in many respects closely analogous to those used, in whole or in part, by plaintiff. So that it is apparent, on inspection of those patents, that every result attempted by plaintiff, as expressed in his claim in this 1878 patent, had been thus attempted, and some of the attempts succesfully, by other inventors to whom letters patent had been issued.

Counsel for plaintiff insists, however, that the real discovery made by complainant was "the method of so rigidly attaching a plow beam to the axle upon which the wheels were mounted as that the bottom of the plow would bear at all times a fixed relation to the furrow wheel." He adds:

"This was the prominent characteristic of the invention,-a characteristic that distinguished the plow in which it was embodied from all prior struc tures."

An insurmountable obstacle to this conclusion is that plaintiff nowhere in his claims, nor even in his specification, announces this as a result attempted or secured. In the original application presented

by him, as well as in that on which his letters patent issued, he states that he has "invented an improved riding attachment for plows." In the original application he commences his specification with:

"The object of my invention is to provide an improved means of carrying a plowman in such a position, relative to a plow. that his weight will aid in making the plow run smoothly and evenly without increasing the draft and labor of the horses, and that he may, by simply adjusting levers at his side, readily govern the width and depth of the furrow, and plow a field uniformly with a common plow without walking."

The specification, as rewritten by plaintiff, and as accompanying the letters patent issued, states:

"My invention relates to that class of plow attachments designed as a means of carrying a plowman in such position, relative to a plow."

-And then follows remainder of specification as above copied. Neither in specification nor claim is there mention or suggestion that his invention bears any relation to, or in any way will affect, the plow, so that "the bottom of the plow will bear at all times a fixed relation to the furrow wheel." If, as stated by Justice Blatchford, supra, "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," the conclusion is irresistible that the afterthought of the inventor cannot control or change his claims, as expressed in the patent, nor the only purpose or result of his invention as he at the time regarded and stated it. It may also be noted that, in his specification, accompanying the letters issued, plaintiff expressly declares, "My invention relates to that class of plow attachments designed," etc., thereby recognizing that plow attachments were then in existence which were designed to effect the result he was seeking to effect by his invention.

As touching the patent issued before the date of plaintiff's 1878 patent, we may note, out of the over 50 patents in evidence, and because of the similarity in many respects to the device of plaintiff as patented, in some of its elements, that at least 10 of these patents claim to effect the raising or elevating of the point of the plow by levers located within the driver's reach as he rides the plow; at least 5 of them effect the "canting" or oscillating of the plow by levers attached to the plow beam; and at least 5 of them have a rear or furrow wheel attached to the plow beam or frame. Especially are the patents issued to Felker (No. 48,387, June 27, 1865) and to Bailey (No. 184,579, May 27, 1876) closely similar to the devices of plaintiff as regards the devices for elevating point of plow and "canting" the plow. Had these two added a furrow wheel, attached to plow beam, it may be doubted whether plaintiff would have been granted any letters patent except on the most restricted claims, in every respect. Was plaintiff, then, a pioneer in this field of invention? It is difficult to define a primary invention, so that the definition shall accurately apply to all inventions. Perhaps as satisfactory consideration of this matter as can be found is contained in the opinion of Jus tice Bradley, in Railway Co. v. Sayles, 97 U. S. 554. The learned justice, in his consideration of the patent involved in that case (railroad brakes) says:

v.72f.no.7-58

"Like almost all other inventions, that of double brakes came when, in the progress of mechanical improvement, it was needed; and, being sought by many minds, it is not wonderful that it was developed in different and independent forms, all original, and all bearing a somewhat general resemblance to each other. In such cases, if one inventor precedes all the rest, and strikes out something which includes and underlies all that they produce, he acquires a monopoly, and subjects them to tribute. But if the advance toward the thing desired is gradual, and proceeds step by step, so that no one can claim the complete whole, then each is entitled only to the specitie form of device which he produces, and every other inventor is entitled to his own specific form, so long as it differs from those of his competitors, and does not include theirs."

After examining the different letters patent relating to plow attachments, and especially riding attachments for plows, it is impossible to escape the conclusion that, within the statement of Justice Bradley above quoted, plaintiff was not a pioneer in the field of invention wherein his letters patent place his claims. Such was the conclusion reached by Judge Shiras, in this court (McBride v. Plow Co., 40 Fed. 162), with regard to plaintiff's 1883 patent. How far, then, is the doctrine as to equivalents applicable to this invention of plaintiff, which we have found to be of a secondary nature? In Miller v. Manufacturing Co., 151 U. S. 186, 207, 14 Sup. Ct. 310, as delivered by Justice Jackson in 1894, appears the following:

"The range of equivalents depends upon the extent and nature of the invention. If the invention is broad and primary in its character, the range of equivalents will be correspondingly broad, under the liberal construction which the courts give to such inventions."

As illustrating the difference, in breadth of liberality of construction, in these respects, between a primary invention and one not primary, we may profitably compare the declaration, in Machine Co. v. Lancaster, 129 U. S. 263, 9 Sup. Ct. 299:

"Where the invention is of a primary character, and the mechanical functions performed by the machine are, as a whole, entirely new, all subsequent machines which employ substantially the same means to accomplish the same result are infringements, although the subsequent machines may contain improvements in the separate mechanisms which go to make up the machine,"

-With the statement of the same justice (Blatchford) in Duff v. Pump Co., 107 U. S. 636, 2 Sup. Ct. 487:

"The case is one where, in view of the state of the art, the invention must be restricted to the form shown and described by the patentee. * * * Todd was not a pioneer. He merely devised a new form to accomplish these results. The defendant adopts another form. Under the circumstances, the Todd patent cannot be extended so as to embrace the defendant's form. The latter is not mere colorable departure from the form of Todd, but a substantial departure."

So, in Rowell v. Lindsay, 113 U. S. 97, 5 Sup. Ct. 507: "The patent being for a combination, there can be no infringement unless the combination is infringed. In Prouty v. Ruggles, 16 Pet. 336, it was said: "This combination, composed of all the parts mentioned in the specification, and arranged with reference to each other and to the other parts of the plow in the manner therein described, is stated to be the improvement, and is the thing patented. The use of any two of these parts only, or of two combined with a third which is substantially different in form or in the manner of its arrangement and connection with the others, is, therefore,