Abstract: A geophone testing apparatus includes a plurality of force detectors upon each of which is mounted a corresponding geophone. An electrical step function is applied to the active elements of the geophones to generate mechanical output transients. The mechanical output transients are detected by the force detectors which generate corresponding electrical signals. The signals are analyzed to determine the sensitivity, damping and natural frequency of each of the geophones under test. A multiplexer is provided so that all of the geophones may be tested at the same time.

Abstract: The electronic roll-along switch consists of several input multiplexers, each having a number of inputs that are connected to seismic detectors, and an output line. A plurality of multiple-input sample-and-hold modules are provided. Corresponding inputs of the respective sample-and-hold modules are paralleled. The output lines of the input multiplexers are connected in consecutive order to the paralleled input of the sample-and-hold modules. The output of each sample-and-hold module is connected to an output amplifier which is couplable to a multichannel seismic recording system. A master controller provides circuitry for connecting any set of several seismic detectors to a like number of channels in the seismic recording system.

Abstract: A decentralized seismic data recording system includes a central station and a plurality of remote seismic recording units that are incommunicado with the central station during a normal recording operation. A master clock is provided in the central station. A local clock is provided in each remote recording unit. At the beginning of a work period, the local clocks are synchronized with the master clock. Thereafter, a plurality of seismic data recordings are made. At the end of a work period, the time difference due to tuning drift between the master clock and each respective local clock is ascertained and is recorded. The time difference is linearly prorated over the recordings made during the work period, thereby synchronizing the time base of each seismic data recording with the master clock. Provision is made to validate each seismic data recording to prevent accidental recording of false data in event of a misfire or a non-fire of the seismic source.

Abstract: A spring-suspended, moving-coil transducer to be tuned is mounted on a dynamic test fixture and excited by an oscillatory driving force calculated to drive the transducer at a desired resonant frequency. A laser beam, sensitive to a difference between the actual resonant frequency of the transducer and the desired resonant frequency, is focused on the spring. The energy of the laser beam alters the elastic constant of the spring by trimming or etching material therefrom until the difference between the actual resonant frequency of the transducer and the desired resonant frequency is eliminated.

Abstract: A hydrogen-purification filter has a closed chamber with a pure-hydrogen outlet. A coil made of thin palladium-alloy tubing is contained in this chamber and has an inlet end and an outlet end accessible from outside the chamber. This coil is of D-section so that in case a leak forms the turn of the coil containing the leak can be excised by cutting at the straight sections on both sides of the leak and the remaining coil rejoined at the straight sections.

Abstract: A combustion chamber especially adapted for use in a high heating capacity, positive-pressure, single-pass radiant heating system employing an oil-fired burner as the heat source comprises a generally cylindrical body having conical ends, one of which has a high degree of taper and is adapted to mount the air tube of an oil-fired burner, and the other of which has a lower degree of taper and is adapted to mount a heating conduit through which combustion products are passed.