1. A RADIATOR ASSEMBLY FOR AN UNDERWATER SOUND GENERATOR COMPRISING, IN COMBINATION, A CASING HAVING A CIRCULAR OPENING IN A PAIR OF OPPOSITE ENDS THEREOF, SAID CASING INCLUDING A CYLINDRICAL BORE SECTION FORMED THREIN ADJACENT ONE OF SAID CIRCULAR OPENINGS; A MAIN PISTON HAVING A CYLINDRICAL BODY PORTION, A PLANAR RADIATING SURFACE, A PLANAR IMPACT SURFACE, AND A CIRCULAR FLANGE PROJECTING FROM SAID CYLINDRICAL BODY PORTION AT A CIRCUMFERENTIAL LOCATION ADJACENT SAID IMPACT SURFACE, THE CYLINDRICAL BODY PORTION OF SAID PISTON FITTING WITHIN SAID CYLINDRICAL BORE SECTION AND CAPABLE OF MOVEMENT THEREIN; AN ANNULAR BELLOWS HAVING AN INNER CIRCULAR RIM AND AN OUTER CIRCULAR RIM; MEANS CONNECTING SAID INNER CIRCULAR RIM OF SAID BELLOWS TO SAID CIRCULAR FLANGE; MEANS FOR CONNECTING THE OUTER CIRCULAR RIM OF SAID BELLOWS TO SAID CASING AT ONE OF SAID CIRCULAR OPENINGS, THEREBY TO CLOSE OFF THAT OPENING; A DIAPHRAGM SECURED TO SAID CASING AT SAID OTHER CIRCULAR OPENING AND CLOSING OFF THAT CIRCULAR OPENING; A GRID OF INTERCONNECTED TUBULAR MEMBERS OF EQUAL DIAMETER RETAINED WITHIN SAID CASING WITH THE LONGITUDINAL AXES OF SAID TUBULAR ELEMENTS BEING PERPENDICULAR TO THE RADIATING SURFACE OF SAID PISTON; A MULTIPLICITY OF FLUID SPRINGS, EACH FLUID SPRING INCLUDING AN ENCLOSED CYLINDRICAL CHAMBER, A PISTON MEMBER HAVING A PISTON HEAD PORTION AND A PISTON ROD PORTION CONNECTED THERETO, SAID PISTON MEMBER BEING ACCOMMODATED WITHIN SAID CYLINDRICAL CHAMBER WITH THE FREE END OF ITS PISTON ROD PROJECTING THROUGH ONE END WALL OF SAID CYLINDRICAL CHAMBER, SPRING MEANS COOPERATING WITH SAID PISTON MEMBER FOR NORMALLY HOLDING SAID PISTON MEMBER AGAINST ONE END WALL OF SAID CYLINDRICAL CHAMBER, A MULTIPLICITY OF APERTURES CUT THROUGH A WALL PORTION OF SAID CYLINDRICAL CHAMBER AT A LOCATION ADJACENT SAID ONE END WALL FOR PERMITTING A FLUID FLOW INTO AND OUT OF THE INTERIOR OF SAID CHAMBER; MEANS FOR LOCKING EACH CYLINDRICAL CHAMBER OF A FLUID SPRING TO A TUBULAR ELEMENT OF SAID GRID IN AN ABUTTING RELATIONSHIP; A FLUID HAVING AN ACOUSTIC IMPEDANCE NEAR THAT OF SEA WATER FILLING SAID CASING AND THE CYLINDRICAL CHAMBERS OF SAID FLUID SPRINGS; AND MEANS CONNECTING THE FREE END OF EACH PISTON MEMBER OF SAID FLUID SPRINGS TO SAID MAIN PISTON AT DIFFERENT POINTS ABOUT ITS RADIATING SURFACE WHEREBY, WHENEVER A FORCE IS APPLIED TO THE IMPACT SURFACE OF SAID MAIN PISTON AND SAID MAIN PISTON DISPLACED WITHIN SAID CYLINDRICAL BORE SECTION, SAID PISTON MEMBERS OF SAID FLUID SPRINGS MOVE WITHIN SAID CYLINDRICAL MEMBERS TO FIRST FORCE SOME OF THE FLUID WITHIN SAID CHAMBERS OUT THROUGH SAID APERTURES INTO THE INTERIOR OF SAID CASING AND THEN COMPRESS THE REMAINING FLUID LEFT WITHIN SAID CYLINDRICAL CHAMBERS.