Abstract: A transducer includes a cup-shaped diaphragm having a planar portion in the form of a flange. The internal space of the cup is closed by a metallic support plate. A disc-shaped piezoelectric element has electrode layers on its front and rear surfaces, and the front electrode layer is joined to the inner bottom of the cup. An electrical lead is connected to the rear electrode layer of the piezoelectric element and extends along the external surface of the support plate after it is passed through the thickness of the plate and then bent at a right angle. A resilient member is joined to the external surface of the support plate, and an aluminium sheet is joined to the resilient member. The diaphragm is connected to the ground through the support plate, and the aluminium sheet is also connected to the ground.

Abstract: An active, low-profile hydrophone for use in aquatic environments having substantially turbulent flow conditions. The hydrophone is generally pisciform such that it may lie substantially flat on the water bottom and oriented in the current so as to reduce ambient noise associated with the turbulent flow. The enclosed sensors are oriented such that they are insensitive to acceleration and are coupled to a unity gain amplifier network also contained within the hydrophone.

Abstract: An apparatus for introducing vibrations into the ground including a container having electrodes mounted therein with electrical connections leading from a source of electric potential to said electrodes, salt water substantially filling the container, and means for placing the container on the ground in position to transmit vibrations to the ground.

Abstract: The insulation resistance between the electroded surfaces of an underwater transducer and the water within which the transducer is immersed is greatly improved by coating the electroded surface of the transducer with a layer of air-free, high-resistance waterproof material before bonding an elastomer covering over the assembly to serve as the outer housing.

Abstract: An improved ocean bottom seismometer is disclosed wherein a skirted spherical configuration provides bottom weight and provides a sealed area for seawater ballast which may be ejected to provide positive buoyancy for retrieval.

Abstract: In accordance with an illustrative embodiment of the present invention, a plug-in geophone case includes a body having an open top and a cavity that receives a seismic detector having positive and negative terminals, receptacles on opposite sides of said body for plugging the case into leader cables, a set of three connector pins molded in the case adjacent each receptacle, one end of each pin extending into a receptacle and the other end extending into a recess in the body adjacent one of said terminals, a cover plate for closing the open top of said case, and means for sealingly fastening a connector plug in each of said receptacles, said plugs and receptacles having mating means to prevent connection with the wrong polarity.

Abstract: A loudspeaker driver has its front surface adjacent one end of a low loss acoustic waveguide and its rear surface adjacent to one end of a second acoustic waveguide that is one third the length of the first. The other openings of the waveguides face air and couple acoustical energy substantially uniformly over a relatively broad range of frequencies extenting into the bass frequency region. An equalizer includes a notch filter so that the frequency response of the equalizer below a bass cutoff frequency is sufficiently low to prevent audible distortion.

Abstract: A seismic detector comprises a casing the lower part (10) of which is provided with a plurality of apertures (19). A hydrophone transducer (70) comprising an annular ceramic member provided with metallized surfaces (71,72) is mounted in the casing and defines with the casing an enclosure (65) which houses a geophone (60). The outer face (71) of the hydrophone transducer (70) is subject to the ambient hydrostatic pressure via the apertures (19). The bottom of the casing is provided with a protuberance (11) to which a spike (12) is attached. The seismic detector can work in both hydrophonic and geophonic modes.

Abstract: This invention includes a seismic detector located in the bottom portion of a casing. The upper portion of said casing contains a printed circuit disc. The printed circuit disc is provided to serve as a junction between the conductor wires of the geophone leader cable and the geophone's terminals, and to anchor the geophone leader cable to the geophone casing.

Abstract: A magnetohydrodynamic geophone for seismological detection. The geophone is of rigid shock resistant design, including a sealed, rigid generally conically shaped housing which is adapted to be firmly embedded within the ground in bedrock or the like, in or adjacent to an area to be seismologically monitored. The shock resistant housing includes an isolated interior for receiving an MHD sensor which detects the seismological vibration. The sensor includes a generally tubular conduit containing an electrically conductive fluid, preferably mercury or an electrolyte. A very strong magnetic field is set up perpendicularly with respect to the plane occupied by the conduit. An electric field is generated through the Faraday Effect in response to vibrations. Preferably the conduit is of ring shaped configuration, and the conductive fluid is continuously circulated throughout it.

Abstract: Disclosed is an apparatus for transducing seismic signals and a method for placing said apparatus for detecting seismic signals. The apparatus comprises at least one geophone preferably embedded in a polymeric material contained in a tubular member. A lower portion of the tubular member preferably contains ballast. The tubular member is preferably cemented into a borehole.

Abstract: The geophone transducer comprises in combination: a geophone capable of detecting horizontal seismic waves, and a rigid casing having a gimbal chamber. A gimbal is provided inside the chamber on which the geophone is mounted for limited free angular movement in one direction only. The gimbal includes in one preferred embodiment a viscous liquid in which the geophone is only partially submerged while it is supported by a U-shaped bracket which is mounted for rotation about a fixed axis.

Abstract: A seismosensitive device comprises a hermetically sealed enclosure having a recess at the bottom, a first annular surface provided around the recess and having a radial gradient substantially of horizontal level and a second annular surface provided around the first annular surface and progressively diverging from the lower to upper portions with a slope having a gradient greater than that of the first annular surface. A switch assembly comprising a drop of mercury placed at the recess, an electrode bar provided with the enclosure, a needle contact secured to the electrode bar to have its lower end immersed into the drop is provided. When the mercury drop moves along the gradient surfaces significantly smoothly to separate from the needle contact upon tremor of the earth, the switch will open.

Abstract: A geophone marsh case, for use in wetlands, contains a geophone. An electric cable delivers geophone signals to the outside world and provides a means for pulling an emplaced geophone from the mud. The cable is anchored to the marsh case both internally and externally in order to preserve the integrity of a water seal that surrounds the cable in the cable entry port of the marsh case.

Abstract: A geophone is hung from a ball bearing in a pendular fashion so that it is free to swing in any direction. Because it is weighted, it will assume the correct positioning for operation. A clamp, carried with the pendular geophone in a seismometer designed for use on the ocean floor, fixes the geophone in a rigid position when a solenoid is actuated. After the seismometer is deployed on the sea bottom, it is desired to clamp the geophone into its assumed position. The solenoid is fired upon command causing the ball to be clamped. When the seismometer is recovered the angle of inclination with respect to the vertical it assumed at the time when the geophone was clamped can be determined by measuring the angle formed by the clamped geophone and a surface known to be vertical when the seismometer rests on a flat, horizontal surface.

Abstract: A waterproof housing assembly for a geophone is disclosed that includes a housing having an elongated cavity. A geophone is mounted in the bottom portion of the cavity. A two conductor takeout cable extends into the cavity that has a first section where the outer sheath and insulation are stripped from the two conductors part of the way back from the end. A second section of the cable adjacent the first has the outer sheath removed from the insulated conductors. A body of elastomeric material is located in the cavity. It has a first pair of spaced openings through which the uninsulated first section of the cable extends to be connected to the geophone, a second pair of spaced openings connected to the first pair in which the second section of the cable is located, and a single opening connected to the second pair in which a portion of the sheathed cable is located.

Abstract: A detector utilizing three seismometers is provided which is operable to detect three components of particle motion waves.

Abstract: Means for mounting a member functioning with a directivity to a mounting station of an associated device or the like. A housing for the member with its functional end surface exposed to the exterior is tapered at the periphery toward the other end to be, for example, hemispherical and rotatably born at diametrally opposed positions adjacent the functional end surface by both ends of a semiarcuate bearing means, the mounting station has a hole including peripherally opposing grooves of a size and shape capable of slidably engaging with the tapered periphery of the housing and receiving semiarcuate body of the bearing means, the housing is inserted in the hole on said the other end side, and the semiarcuate body of the bearing means in the inserted position of the member engages slidably with a resilient means acting to resiliently urge the tapered periphery of the housing against peripheral edge of the hole.