1. MULTIPLE PRESSURE RESPONSIVE CONTROL APPARATUS COMPRISING A PLURALITY OF FLUID PRESSURE-SENSING DEVICES, EACH HAVING A RECIPROCABLY MOUNTED SHAFT; MEANS FOR FIXEDLY MOUNTING SAID SENSING DEVICES WITH THE AXES OF RECIPROCATION OF SAID SHAFTS DISPOSED IN SUBSTANTIALLY PARALLEL RELATION IN A SINGLE PLANE; AN ACTUATOR ROD DISPOSED IN A FIRST POSITION ADJACENT TO THE PLANE OF MOVEMENT OF, BUT SPACED FROM, SAID SHAFTS; MEANS MOUNTING SAID ROD FOR LIMITED MOVEMENT FROM SAID FIRST POSITION TO A SECOND POSITION IN A DIRECTION AWAY FROM THE PLANE OF MOVEMENT OF SID SHAFTS; A CONTROL DEVICE; MEANS CONNECTED TO SAID ROD FOR ACTUATING SAID CONTROL DEVICE WHEN SAID ROD IS MOVED IN SAID DIRECTION FROM SAID FIRST TO SAID SECOND POSITION; MEANS FOR CONNECTING EACH OF SAID SENSING DEVICES TO A SEPARATE SOURCE OF PRESSURIZED FLUID; PRESSURE RESPONSIVE MEANS IN EACH SENSING DEVICE FOR MOVING THE SHAFT THEREOF IN RESPONSE TO CHANGES IN, AND MAINTAINING THE LINEAR POSITION OF SAID SHAFT IN ACCORDANCE WITH THE MAGNITUDE OF, THE FLUID PRESSURE OF THE SOURCE TO WHICH THE SENSING DEVICE IS CONNECTED; AND AT LEAST ONE ACTUATING MEMBER MOUNTED ON EACH OF SAID SHAFTS AND HAVING A SURFACE ENGAGEABLE WITH SAID ROD WHEN ITS RESPECTIVE SHAFT IS RECIPROCATED TO A PREDETERMINED POSITION RELATIVE TO SAID ROD, SAID ACTUATING MEMBER SURFACES OF SAID SENSING DEVICES BEING LOCATED ON THEIR RESPECTIVE SHAFTS SO AS TO BE OUT OF CONTACT WITH SAID ROD WHEN SAID SHAFTS ARE RECIPROCATED BETWEEN POSITIONS CORRESPONDING TO PREDETERMINED MANGITUDES OF THE FLUID PRESSURE OF THEIR RESPECTIVE SOURCES, AN ACTUATING MEMBER SURFACE OF ANY ONE OF SAID SENSING DEVICES BEING ADAPTED TO ENGAGE SAID ROD INDEPENDENTLY OF THE POSITIONS OF THE SHAFTS AND ACTUATING MEMBER SURFACES OF THE OTHER OF SAID SENSING DEVICES, AND TO INDEPENDENTLY MOVE THE ROD IN SAID DIRECTION FROM SAID FIRST TO SAID SECOND POSITION TO ACTUATE SAID CONTROL DEVICE WHEN THE SHAFT OF SAID ONE SENSING DEVICE IS RECIPROCATED TO A POSITION CORRESPONDING TO A FLUID PRESSURE OF ITS RESPECTIVE SOURCE WHICH DEVIATES FROM A PREDETERINED MAGNITUDE IRRESPECTIVE OF WHETHER ANY OF SAID ACTUATING MEMBER SURFACES OF SAID OTHER OF SAID SENSING DEVICES IS IN CONTACT WITH SAID ROD.