Abstract: A device is provided for generating acoustic waves by means of a falling mass striking a target element integral with rectractable anchorage means. The mass moves in an elongate body under the combined action of gravity and resilient means from a raised position to an impact position. Resetting, after the fall, is provided by raising the mass by means of a nut, held against rotation, using a threaded rod connected to reversible drive means and locking it in the high position either by means of a retractable bar tripped by the return of the nut to the low position or else by remote controlled magnetic means. The anchorage means include for example a "packer" and a resilient coupling means.

Abstract: A lifting device is provided for rapidly coupling and uncoupling a floating load, such as a boat, when it is set afloat or raised from the water. It includes essentially a hook secured to the load and a coupling element connected by cables to a lifting appliance. The concavity of the hook is turned downwards. Its section is trapezoidal and tapers towards its tip. The coupling element includes two arms whose facing walls are slanted and guide the hook towards the central housing. Springs, disposed laterally in the housing, come to bear against the lateral slanting faces of the hook and prevent it from leaving again.

Abstract: A device for receiving acoustic waves in water and adapted to be positioned vertically in the water in a stable position. The device comprises a tubular element formed of several connected sections, buoyancy means close to a first end, ballasting means close to the second end, several receivers spaced apart inside certain sections of the tubular element and stabilizer fins fixed to the second end thereof. A cable connects the tubular elements to a towing vehicle.

Abstract: The device includes two movable members interconnected at their periphery by a flexible membrane defining therewith a tight enclosure of variable volume, a piston slidable in a cylinder integral with one of the two movable members and hydraulically actuated, to move the members apart from each other, a second cylinder separated in two compartments by an inner valve and controlling the actuation of the piston in response to the pressure of the water feeding said second cylinder, two apertures intermittently freed by the valve for releasing the piston and at least one aperture for the discharge of the water from the tight enclosure to the external water body when the piston release allows the two movable members to be urged toward each other, thereby producing an implosion which generates a strong sonic wave.

Abstract: Device for generating acoustic waves by implosion in a fluid medium comprising fluid-operated means to move a piston, having one end face in contact with said fluid, from a retracted position in the enclosure to a spaced apart position of maximum extension towards the exterior of the enclosure or vice versa and intermittent locking means for maintaining the piston at its spaced apart position, said fluid-operated means being actuated by two sources of fluid at different pressures, one of which is said fluid medium and the other a source of lower pressure.

Abstract: This device comprises two movable elements of rigid material tightly interconnected by means of a deformable membrane forming therewith a tight internal enclosure, means for varying abruptly the volume of said enclosure by successively moving the two elements away from each other, maintaining them in spaced relationship and allowing them to be urged toward each other by the effect of the external hydrostatic pressure, in which the means for moving the two elements away from each other includes two cylinders and at least one piston slidable in one of said cylinders, associated to one of said movable elements and also to a push-member slidable in one of the cylinders and bearing on the other movable element and means for feeding said cylinder with pressurized fluid so as to maintain the elements in spaced relationship or to release them.

Abstract: A device for transmitting acoustic waves through a liquid medium in which it is submerged comprising two movable assemblies including respectively members provided with first contact walls and delimiting with a sealing membrane a water tight enclosure, and members provided with second contact walls which are the armatures of an electro-magnet, the respective members being so arranged that when the first contact walls are in contact, the second contact walls are spaced apart and conversely, pressure actuated means for moving the first contact walls apart from each other and releasable locking means including an energizing coil for maintaining the armatures of the electro-magnet in spaced apart relationship.

Abstract: This device comprises two movable elements of rigid material tightly interconnected by means of a deformable membrane forming therewith a tight internal enclosure, means for varying abruptly the volume of said enclosure by successively moving the two elements away from each other, maintaining them in spaced relationship and allowing them to be urged toward each other by the effect of the external hydrostatic pressure, in which the means for moving the two elements away from each other includes two cylinders and at least one piston slidable in one of said cylinders, associated to one of said movable elements and also to a push-member slidable in one of the cylinders and bearing on the other movable element and means for feeding said cylinder with pressurized fluid so as to maintain the elements in spaced relationship or to release them.

Abstract: Shock absorber comprising a casing delimiting an inner recess having two portions of different diameters and containing a liquid, a piston assembly consisting of two pistons of slightly different diameters mounted on the same rod and slidable into said recess, the larger of said pistons being traversed by a channel for liquid passage, a liquid reservoir either inside the rod or outside the casing, in communication with the inner recess through a further channel, sealing structure tightening the recess from the external medium and an element in the reservoir which is compressed or expanded in response to a change in the pressure of the liquid contained in the reservoir.