This patent covers an improvement on an earlier device, the patent for which is considered in an opinion handed down at the same time with this one. The socket as thus improved has an additional protection against rotation by a cut-metal engagement of parts 19 and 20. We think the improvement was novel and' meritorious and concur fully with Judge Ray’s reasoning and conclusions..

We think, however, that he erred in holding the second claim to be valid. The first two claims read as follows:

“1. In a device of tbe class described and in combination, a pair of tubular, sheet-metal members, one adapted to telescopically receive tile other, having *951mutually abutting cut-metal edges on the respective members to prevent relative rotative movement, and automatically interlocking means for preventing a telescopic movement of separation of one member from the other, said means permitting, without manipulation thereof, the telescopic application of the members to each other.

“2. In a device of the class described and in combination, a pair of interlocking, tubular sheet-metal members, one adapted to telescopically receive the other, having mutually abutting cut-metal edges on the respective members to prevent a telescopic movement of separation of one member from the other when interlocked; and having other interengaging means for preventing a relative rotative movement of the interlocked members.”

[1] Claim 1, it will be observed, specifies the means for preventing relative rotative movement, viz., “mutually abutting cut-metal edges on the respective members.” This means we are satisfied was patentable being an advance over whatever other means in the prior art had been employed to prevent relative rotation. But the second claim calls merely for “other interengaging means” for preventing relative rotation. This phrase would cover all the various interengaging means of the prior art, but the advance is a narrow one and the patent can be sustained only for the precise means which the patentee showed would accomplish the result. If claim 2 stood-alone it might be saved by reading into it the specific device, but if this were read in it would be a mere duplicate of claim 1.

[2] With the elimination of claim 2 the decree of the District Court is affirmed, with five-sixths costs of this appeal to complainant.