Abstract: The level or tilt angle of the surface of a bed of solids in the round portion of an elongated rotatable chamber is determined by directing a collimated gamma ray beam transversely through the chamber to a scintillation radioactive count rate detector. The chamber is either horizontal or inclined from horizontal at an angle of less than 30.degree.. At least three equal length transversely spaced apart radioactive scans or measurements with the source located at three different points are required. The scans must lie in approximately the same transverse plane and one of the scans must be transversely located between the other two scans. Best results are obtained when at least four scans are taken with the transverse plane of the scans perpendicular to the longitudinal axis of the chamber. The method will usually be applied at a number of axial points under dynamic conditions so that the contour of the bed may be plotted.

Abstract: A hand-held, caliper-like detector suitable for measuring the level of a nongaseous substance in a cylinder has two extending arms. The arms of the caliper-like detector are adapted to extend around a part of the cylinder. A gamma radiation source is located on one arm and is adapted to emit gamma rays through a segment of the cylinder toward a scintillator. The scintillator is located on the second arm and is adapted to receive the gamma rays emitted by the radiation source. Various embodiments of the detector pertain to positioning of the radiation source, shielding the source when not in use, the angle subtended by an imaginery chord joining the source and scintillator, and fabrication of source and scintillator housing.

Abstract: The level of liquid or solid substances in a cylindrical chamber is detected using a radioactive source and detector mounted on a vertically movable member in horizontally spaced fixed relation to each other in a manner such that the source and detector measure across a horizontal sector of 90.degree. or more of the cylinder in which the level of the solid or liquid is to be measured. Vertical movement of the source and detector is accomplished through a drive means whose action is correlated with a recording chart on which is simultaneously plotted the amplitude of the signal produced by the detector.

Abstract: Method and apparatus for electrical logging in a mud-filled borehole by sensing redox potential and other formation characteristics. An elongated, tubular probe body contains reference and potential measuring electrodes which extend longitudinally thereof and are adapted to make external contact with the borehole fluid at the streamlined surface of the probe nose. The metal reference electrode member is immersed in an electrolyte-filled compartment separated from the external borehole fluid by a pressure-compensating diaphragm in the probe side wall, a fluid bridge with the mud of the borehole being established through a permeable ceramic wick. Probe design insures adequate mud flow past the electrodes in a nonturbulent state as the probe is lowered, thus eliminating clogging and providing good electrical contact. Alternate means are provided for maintaining a positive leak pressure regardless of borehole conditions.

Abstract: A gas exploder for injecting seismic signals into the earth is provided with a high speed hydraulic catching apparatus which allows the exploder to rebound essentially unrestrained after it is fired at the surface and replaces it on the ground in one second or less without generating a significant false signal. The exploder falls freely from its maximum rebound height to within a few inches of the ground and is then lowered slowly to its starting position. Means are provided for automatically adjusting the position of the exploder after each shot so that it rests on the earth ready for the next firing even though compaction of the earth has taken place.

Abstract: A method and apparatus for recording the position of a sensor to reduce turbulence errors in airborne magnetic surveying includes, in one embodiment a camera mounted on a gyrostabilized platform to maintain it at a constant downward orientation from a bird towed from an airplane. The bird, in addition to the platform and camera, carries a magnetometer sensor which measures the magnetic field at the bird at a predetermined rate. The camera is actuated at the times the magnetic field is measured, whereby the position of the magnetometer can be precisely located for each measurement taken. In another embodiment, two birds towed from an airplane each carries a magnetometer sensor. The two birds are towed at different altitudes, one above the other, and a camera is carried by the bird at the higher altitude to photograph the bird at the lower altitude and the earth to precisely record the relative locations of the birds with respect to each other and the earth when the magnetic measurements are made.

Abstract: A seismic gas exploder is coupled to the movable piston of a hydraulic catching system so that the piston is constrained to move with the exploder as it rebounds upward from a shot and then falls back to earth. The weight of the gas exploder is applied through the piston to increase the pressure of the hydraulic fluid in the system when the exploder is moving in a downward direction. A two-position diaphragm actuated pressure switch monitors the fluid pressure, the position of the switch contacts being effective to control an exploder firing circuit or provide other indication of the exploder's position.