The Bureau of Mines Spokane Research Center has constructed an intrinsically safe closure-rate instrument that provides the mine operator a means for predicting an imminent roof fall during pillar robbing. This improves operator and machine safety and prevents delays in digging out equipment. The instrument system consists of two rugged retrievable extensometers connected by long electrical cables to a digital readout unit for reading closure and closure rate. Once a predesignated closure rate is reached, the extensometer is retrieved by pulling it from the imminent roof fall area by the electrical cable. The equipment and mine personnel are also pulled back to await the fall, which usually occurs within minutes after the designated rate is reached. Although the unit is primarily designed for retreat mining operations, it can be used for any activity requiring measurement of displacement or rate of displacement with a measurement range of zero to 6 inches with 0.1 percent accuracy for openings 4 1/2 to 12 feet.