Abstract: An area is surveyed for variation in a physical characteristic or property which is effective for modifying nuclear radiation of a predetermined type through the use of an apparatus and in accordance with a method in which the modifying characteristic is measured by applying nuclear radiation while generating a signal representative of the measured characteristic, the generated signal is registered in the programmable memory device, the steps of measuring while generating and registering are thereafter repeated, and the information gathered is transmitted for retrieval and processing at a remote location.

Abstract: A method, and a nuclear radiation gauge, for surveying a roof for moisture in which a thermal neutron gauge is positioned at a predetermined location on a roof, the signal representative of the hydrogen content of the roof at that location is generated and registered in a programmable memory device, and the gauge is then moved to a succession of predetermined locations arranged in a predetermined array on the roof while repeating the steps of generating and registering signals at each location.