delivered the opinion of the court affirming the decree of the circuit court.

Letters patent claiming, “ in combination with a stove door, a hinged shelf, fitted to fall outward and down automatically when the oven door is opened and to be raised up by closing the oven door, adapted to operate on it for that purpose,” covers only the specific devices for raising and lowering the hinged shelf, and as both devices claimed operate upon the same principle precisely *352as that which has been used for a long time for other similar purposes, and as defendants use a different device, they are not guilty of infringement.