Abstract: A geophysical exploration system uses a single conductor cable connected to a current source, the cable having a number of earth probes coupled to it at spaced points with addressable switching units. The switching units are activated in sequence so that the probes inject current into the earth. At locations spaced from the probes the resistivity is measured and recorded for each injection. Resistivity measurements are compared with anomaly models to find a match of patterns, indicating the presence, size and location of an anomaly.

Abstract: A system for monitoring the operation of a heating apparatus having a combustion chamber with associated air and fuel supplies and an exhaust path includes sensors for monitoring temperatures at the combustion chamber. A microprocessor and a display receives signals from these sensors and has a keypad to permit calculation and display of parameters indicative of proper operation of the heating system including fuel usage per unit time. Limit values can be stored in the processor memory to trigger alarms when temperatures or fuel usage exceed the set limits. Various measured and calculated values can be displayed.