Although electromagnetic induction loggers have been used by the oil industry for many years their sondes are generally unsuitable for groundwater applications, for which the requirements are 1 . Slim probes (monitoring Wells are often only 5 cm in diameter) 2 . Good vertical resolution, so as to resolve thin contaminant plumes, combined with a moderate radial depth of investigation (of the order of 1m) 3 . Low noise and good stability so as to measure background conductivities as low as 1 mS/m (1000 ohmm ) 4 . Linear response with conductivity to about 3000 mS/m (0 .3 ohmm ) 5 . Modest depth of exploration, seldom in excess of 250 m, and lastly 6 . The overall system (including winch and console) must be compact, lightweight and relatively inexpensive .