Abstract: A toroidal liquid filled sensor measures rotation with respect to vertical in any plane normal to the earth's surface and comprises a sealed, non-conductive, hollow toroidal housing of square or rectangular cross section with an interior circular cavity or channel of like cross section. A discontinuous resistive strip circles the interior surface of the channel outer wall and a continuous conductive strip or collector circles the exterior surface of the channel inner wall. Electrical contacts are connected to each end of the resistive strip and a third contact is connected to the collector. The channel contains a quantity of dielectric or resistive fluid which has total volume less than a 30.degree. sector of the channel. Electrical damping (R-C time constant) is achieved by balancing the capacitance and resistance parameters. A single sensor has a linear range greater than 270.degree.. The combination of two sensors allows measurement of full 360.degree.

Abstract: For use in transmitting acoustic waves propagated along a well drilling string, a piezoelectric transducer is provided operating in the relatively low loss acoustic propagation range of the well drilling string. The efficiently coupled transmitting transducer incorporates a mass-spring-piezoelectric transmitter combination permitting resonant operation in the desired low frequency range.

Abstract: The operation of a geothermal well power-generationsystem is monitored by sensor, communication, and performance monitoring equipment normally associated integrally with the operating power generation system. Sensors detect magnitudes of well water temperature, of water pressure below and above the pump, and of other parameters of interest deep in the well. This data is transmitted by multiplex communication via a novel two-wire line telemetric system to receiver and utilization means at the earth's surface. Power for excitation of deep well monitor units is supplied from the earth's surface also by the two-wire telemetric system. A configuration involving a mechanically separable transformer disposed serially within the two-wire line aids installation of the monitor system and its removal in the rare event that it is required to remove the entire pump from its operating deep well site.