The sole question is that of invention, for, if the patent is valid, it is infringed. This is a crowded art, punctured by gradual mechanical improvements, consisting mainly in a rearrangement of fundamental elements.

Jakobson’s safety cock for gas burners is undoubtedly a meritorious improvement over the prior art, and, within modest limits, has been commercially successful. But the improvement is of a character familiar to the courts, as within the expected knowledge of one skilled in the art. The simple nature of the art does nqt need exposition. Of the prior art, it is enough to cite Jakobson, No. 685,612; Shute, No. 756,066; Brown, No. 759,341, showing the centering projection; and Mattice No. 792,531. The only difference between the claim of the Shute patent and the patent in suit is that in the Shute patent the socket is in the lever, instead of the plug—a reversal of parts.

The Shute patent does not show a centering projection for the spring; but this is an ordinary mechanical expedient, as witness the Brown patent, supra. In view, of the foregoing, it must be held that the improvement of Jakobson does not rise to the dignity of invention.

Bill dismissed, with costs.