188 F. 73 | 2d Cir. | 1911
The patent in question relates to a combination in a spark-plug composed of the following elements:
1. A socket, having a screw-thread and a shoulder.
2. A shank of insulating material having thereon an enlargement adapted to rest on said shoulder and tapering upward from said enlargement.
3. A threaded hushing surrounding said tapered portion, screwing upon said socket and adapted to press against said tapered, portion, the lower edge of said hushing being sharpened and formed of soft metal and adapted to be upset when screwed down upon said tapered portion.
The invention resides in the third element — the bushing. Mills was the first to produce a spark-plug bushing having a lower edge of soft
The other prior devices and patents principally relied on by the defendant are discussed in the opinion below and we agree with what • is there said regarding them.
The invention is, of course, a narrow one, but it belongs to that large class where the courts have sustained improvements over the prior art, which produce a new and beneficial result that materially advances the art to which they belong. When a defendant persists in using such an improvement in preference to prior devices which he insists are equally efficacious, he tacitly concedes its superiority. It is difficult to reconcile his persistent use, even though it involves him in an infringement suit, with the contention that other devices which he is free to use are equally good.
Infringement is clear. The defendant’s bushing is an exact counterpart of the patented structure except that the bevel of the lower or sharpened edge is not so pronounced, more force being required to produce the outward pressure, or upsetting, when the bushing is screwed down. That the lower edge is upset and performs the identical function of the-bushing of the patent is too plain for argument. The hugging contact is there,-only in a less degree.
The decree is affirmed.