The proof of the use of grain-car doors by the defendant was contained in a stipulation whereby it was agreed 'that the defendant had hauled over its line of road, in the state of Indiana, freight-cars belonging to the Chicago, Rock Island & Pacific Railway Company, having a solid outside door, like an ordinary freight-car, and an inner flexible sliding grain-door of less height than the opening in the side of the car; the grain-door sliding in grooves like the grooves shown in the patent of Martin M. Crooker, of May 26, 1868, and the slats composing the door being attached to each other by being strung upon wires passing through the slats.' Watson's application was dated February 18, 1878, and contained the following claims: '(1) A grain-door, constructed of longitudinal sectional pieces, hinged or strapped together in such manner as that the door, as a whole, may yield, to follow any desired line of movement, when it is not in use as a grain-door, and it is desired to place it out of the way, substantially as herein described. (2) A grain-door, D, constructed as above described, and hinged or strapped so as to be flexible or yielding, for the purpose set forth, in combination with the guiding rods, C, whereby, when not in use, it may be carried up and placed in the horizontal portion of said guiding rods, so as to be out of the way, substantially as described. (3) A grain-door, D, constructed as described, and provided with staples, c, c, in combination with guiding rods, C, and devices for affixing it to the top of the car, substantially as described, and for the purposes set forth.' The application was rejected March 8, 1878, the examiners stating: 'This 'grain-door' differs from Crooker's (May 26, '68, No. 78,188, carpentry doors) 'railroad car' only in the name, and in this: that the upper portion of Crooker's door is cut off to make applicant's. The rods and staples are substitutes for Crooker's channel-irons,—obvious to any skilled workman.' Watson then, on the 18th of March, 1878, amended his specification by inserting: 'This invention relates to improvements in the class of graindoors for cars, and the invention consists in the combination, with a car, of an inside vertically sliding flexible or yielding door and guiding rods, whereby the door, when not in use, may be carried up and placed on the horizontal portion of said guiding rods, so as to be out of the way.' 'I am aware that a car-door of similar construction, sliding in grooved ways, is old; and such I do not desire to claim, broadly, as my invention. Said door, however, constitutes an outside or closing car-door proper, and the car could not* be loaded or used for bulk grain unless the grain is put in from the roof of the car, as the door completely closes the doorway or opening. Furthermore, said door is obviously objectionable for other reasons, viz.: The grain will lodge or get in the grooved ways in which the door slides, binding or locking it so as to prevent its being raised, and also, being an outside door, the grain, pressing against it, would force or bulge the door outward, producing a similar effect as the grain lodging in the grooved ways; whereas my door, being an inside door, and not reaching the top of the doorway or opening, admits an open space at the top for loading in the grain, with an ordinary outside door, to be locked or otherwise secured after the car is loaded. By also employing guiding rods for the door to slide upon, and being an inside door, the defects incident to the grooved ways and an outside door, before referred to, are entirely obviated.' And at the same time he substituted for his first and second claims the following: '(1) The combination, with a car, of an inside flexible or yielding and vertically sliding grain-door and guiding rods, C, whereby said door, when not in use, can be carried up and placed on the horizontal portions of said guiding rods, out of the way, substantially as and for the purpose herein shown and described.' March 20th, the application was again rejected, the examiners stating: 'It is not considered that Crooker, in removing the upper few slats of his door, would be making a patentable improvement on his own invention, albeit he might change its name, and allege the result of loading in over the top of his door. The change is an obvious one to any user of freight-cars; further, the use of rods and eyes is old in this connection. See patent of H. L. Clark, Aug. 29, '71, No. 118,514, (carpentry doors,) which further confirms the former action in relation thereto. In regard to the clogging and binding referred to in argument, no clear or considerable results are seen to be accomplished by applicant's device over the reference, such as should argue any invention thereon.' Watson then, on the 21st of March, 1878, further amended by substituting for the first and second claims the following: 'The combination, with a car, of an inside flexible or yielding sliding grain-door, having staples, c, and the vertical and horizontal bent guiding rods, C, extending from the floor of the car upwardly, and under the roof of the car, as herein shown and described, whereby said door, when not in use, can be carried up on the horizontal portions of said guiding rods, out of the way, substantially as specified.' The examiners again responded, March 23, 1878: 'The application does not present patentable novelty over Crooker, cited. In view of the state of the art as shown by the references cited, the use of eyes and rods for guiding the sliding door are the simple mechanical equivalents of the channel irons of Crooker. As claim does not differ in a matter of substance from the preceding, it is a second time rejected.' An appeal was prosecuted to the examiners in chief, who reversed the decision, saying: 'The invention in this case is small, and the claim is correspondingly limited. It consists of a combination of various instrumentalities not found in either of the references. Applicant's car, as a whole, is adapted by convertibility to uses not compatible with the cases cited, without injury. In this case the flexible door is applied in addition to the usual slide-doors, and when coarse freight is to be carried the flexible shutters are secured in place at the top under the roof of the car.'

The door in use upon the freight-cars which appellee hauled over its road was a grain-door sliding in grooves. The Watson door was carried on rods with staples. Even if there was no material difference between a doorsliding in grooves and a door sliding on rods and staples, there was no infringement, for Watson had in effect disclaimed a door sliding in grooves by his amendments, and the terms of his specification as they stood amended; and in the narrow claim of his patent the staples, c, and the guiding rods, C, were part of his combination, which he could not, under the circumstances, say were not essential to it, nor that the grooves were an equivalent. Gage v. Herring, 107 U. S. 640, 2 Sup. Ct. Rep. 819; Fay v. Cordesman, 109 U. S. 408, 3 Sup. Ct. Rep. 236. But counsel for appellant insists that Watson's real invention 'was not a question of rods or grooves, but was the combination, in a freight-car having an outside rigid door, of an inner flexible sliding grain-door.' The Crooker door was patented May 26, 1868, and made of separate strips attached to each other by long continuous metal straps, so as to be flexible, and capable of being slid up out of the way, under the roof of the car, in grooves of channel irons affixed to the inside of the door-posts, but was a full, and not a half, door. One of the doors was an inside door, as appears from the drawings, and was described in his specification as follows: 'B, B, and B', B', are metallic grooved ways applied at the margin of the door-spaces, d, d, and partially across the car, immediately under the roof of the same; the vertical portions of the ways, B', B', being on the inside of the car, just at the edge of the said spaces, and firmly bolted in place upon the car-framing; or, if preferred, these vertical portions may be in the door-space itself, as is the case with those of the ways, B, B.' The Clark patent was issued August 29, 1871, for a rigid grain-door, filling only half the opening, and sliding on rods to the top of the car, where it was then swung up into a horizontal position, turning on eyes at the upper corners of the rods. The evidence established that inside graindoors, filling only part of the opening, had long been used on freight-cars in connection with the outside door. Watson's door was made of separate slats, united to each other by hinges, and provided with staples at both ends, that encircled the guiding rods, on which the door might be slid up under the roof of the car, so as to be out of the way. Making Crooker's door smaller, so as to fill only half the opening, and using it in connection with an ordinary outside door, in combination with a car, is the invention claimed. We agree with the learned judge holding the circuit court when he says, 'There is nothing in either specification or claim concerning 'ordinary freight-cars, nor solid sliding outside doors; and in the claim, nothing about outside doors at all, unless inferred from the description given of an inside door. If, however, such an inference is permissible, and the patent must or may be construed to consist in such a combination of inside and outside doors as is asserted, it cannot be upheld, because it does not involve invention, but consists in a mere aggregation of parts, each to perform its separate and independent function, substantially in the same manner as before combination with the other, and without contributing to a new and combined result. The outside door certainly remains unaffected in construction and in use; and the inner door is the same as the Crooker door, with a few slats left off or taken off by design or by accident; and, whether done in one way or the other, the change cannotreasonably be called 'invention,' unless the distinction between mere mechanical skill and inventive genius is to be disregarded.' There was nothing new in flexible or rigid doors, outside and inside. There was nothing new in the use of outside and inside rigid doors in combination, the inside door filling only part of the opening. The substitution of the old flexible sliding inside door, reduced in size to correspond with the old inside rigid grain-door, may have required some mechanical skill, and may have been new and useful, but it did not involve the exertion of the inventive faculty, and embraced nothing that was patentable. Thompson v. Boisselier, 114 U. S. 1, 11, 12, 5 Sup. Ct. Rep. 1042, and cases there cited; Stephenson v. Railroad Co., 114 U. S. 149, 5 Sup. Ct. Rep. 777.

The decree was right, and it is affirmed.