Abstract: A miniature, low power consuming, density gage utilizing extremely small artificial and naturally found radioactive sources. The gage employs a unique method of compensating for the gamma attenuation coefficient in different materials such as soils to provide a very simple but accurate and effective moisture gage. A single source emits radiation beams, one through a control sample of the material and at least one beam through a zone of the material where moisture content is to be determined. The apparatus may optionally be employed to control a crop irrigation system to maintain moisture within the comfort zone of the plants growing in the soil. The invention also may be used for measuring moisture content in several discrete zones of the material.

Abstract: Selected variables of a fluid flowing through a conduit are measured by transmitting acoustic pulses through the conduit wall and fluid stream along normal and oblique transmission paths between acoustic transducers located externally of the conduit, measuring the transit times of the pulses between the transducers, and combining these transit times with certain conduit and transducer parameters according to predetermined mathematical relationships to obtain the values of the variables. The variables which may be measured are flow velocity, mass flow rate, sonic velocity of the fluid, fluid compressibility, fluid temperature, and fluid density.

Abstract: A solid, annular body embedding naturally occurring radioisotopes, forms a source of radiation bordering the opening of a basin at ground level, into which water percolates from a body of precipitation in the form of snow and ice accumulated on a porous cover closing the opening. Point detectors above the opening and below the basin sense radiation emitted from the source to produce signals attenuated by the accumulated precipitation reflecting changes in density thereof. Other detectors laterally spaced from the source of radiation both inside and outside its signal range, respectively measure changes in soil density and background radiation.