1. A CUTTING MACHINE COMPRISING A KNIFE, MEANS FOR DRIVING SAID KNIFE IN A CIRCUIT AROUND THE EDGE OF THE ARTICLE TO BE CUT, A FIXED FORM ENCOMPASSED BY SAID CIRCUIT, A TABLE FOR CARRYING STOCK FROM WHICH ARTICLES ARE TO BE CUT INTO THE PATH OF SAID KNIFE AND FOR CLAMPING SAID STOCK AGAINST SAID FORM, A FIRST CYLINDER FOR MOVING SAID TABLE TOWARD AND AWAY FROM SAID FORM, CLUTCH MEANS FOR CONNECTING AND DISCONNECTING SAID DRIVING MEANS FROM SAID KNIFE, A SECOND CYLINDER FOR ACTUATING SAID CLUTCH MEANS, A REGULATED SOURCE OF PRESSURIZED FLUID, A FIRST VALVE ACTUATED BY SAID SECOND CYLINDER, AND A MANUALLY OPERABLE SELECTOR VALVE, SAID FIRST CYLINDER COMMUNICATING WITH SAID REGULATED SOURCE THROUGH SAID FIRST VALVE AND THROUGH SAID SELECTOR VALVE IN A FIRST POSITION OF SAID SELECTOR VALVE, AND SAID FIRST CYLINDER COMMUNICATING DIRECTLY WITH SAID REGULATED SOURCE THROUGH SAID SELECTOR VALVE IN A SECOND POSITION OF SAID SELECTOR VALVE.