1. IN A DEVICE FOR CONTROLLING THE TRANSVERSE MOTION OF A TOOL CARRYING SLIDE ACROSS A LONGITUDINALLY RECIPROCABLE SADDLE IN A MACHINE TOOL, INCLUDING A STATIONARY TEMPLET, A FEELER ADAPTED TO BE CARRIED BY SAID SADDLE AND BE RECIPROCATED TOGETHER WITH THE LATTER ALONG SAID TEMPLET IN ORDER TO COOPERATE THEREWITH, STATIONARY SLIDE ACTUATING MEANS RESPONSIVE TO SAID FEELER THEREBY AUTOMATICALLY TO ACTUATE SAID TOOL CARRYING SLIDE AWAY FROM A WORK PIECE FOR A PREDETERMINED RELATIVE ENGAGING POSITION OF SAID FEELER AND TEMPLET, WHEREBY MOVING SAID TOOL OUT OF ENGAGEMENT WITH THE WORK PIECE, AND RESTRAINING MEANS ADAPTED TO RESTRAIN SAID ACTUATING MEANS FROM MOVING SAID SLIDE BACK TOWARDS THE WORK PIECE UPON DISENGAGEMENT OF THE FEELER FROM THE TEMPLET, SAID RESTRAINING MEANS COMPRISING A MOVABLE FINGER CARRIED BY THE FEELER AND ADAPTED TO MOVE INTO A POSITION WHERE IT EXTENDS BEYOND THE SENSING FEELER END AND IN ABUTTING ENGAGEMENT WITH THE TEMPLET AGAINST THE THRUST OF SAID ACTUATING MEANS WHEREAS THE FEELER IS OUT OF ENGAGEMENT WITH SAID TEMPLET, SPRING MEANS BIASING SAID FINGER TO URGE IT TOWARD SAID ABUTTING POSITION, SAID MOVABLE FINGER BEING FURTHER ADAPTED TO BE MOVED AND RETAINED BY SAID TEMPLET AGAINST SAID SPRING MEANS OUT OF SAID ABUTTING POSITION BY REENGAGEMENT WITH SAID TEMPLET UPON DISENGAGEMENT THEREFROM DURING RETURN STROKE OF THE SADDLE, SAID FINGER BEING THUS SWEPT ALONG SAID TEMPLET DURING MACHINING STROKES OF THE SADDLE.