The Model 54-A soil resistivity apparatus is lightweight, accurate and simple to operate. It lends itself equally well to spot checks of soil or water resistivity, or to detailed investigations typical of pipeline survey work.
The complete apparatus consists of a 40" calibrated hexagonal steel rod with handles and insulated tip, a compact AC resistivity bridge instrument in a leather carrying case, and an ear set for balancing a bridge by null method. The rod is simply pushed into soil to the desired depth and connected to bridge. AC resistance between the tip and body of rod is determined by balancing bridge and soil resistivities in Ohms-cc read direct on the dial.
The soil rod is made of cold drawn hexagonal steel with a hardened steel tip insulated by a nylon washer. The Connecting lead from the tip is brought up through the body of the rod to the insulated terminal. The other terminal is grounded to the body of the rod. Units are furnished complete with soil bridge, rod, case, ear set, connecting leads, and instructions.
The bridge weighs only 1 3/4 pounds and is neatly assembled in a 6" x 3" x 2 1/2" polished ebony bakelite case. The rod is lightweight yet rugged for field usage. It may be used with any standard resistivity bridge and is also very useful as a pipe locating and contact bar for taking pipe potential measurements and long line currents.