A movable array composed of Ranger type seismometers, 60-day film recorders and 7-day magnetic tape recorders housed in compact trailers, has been developed. The array is useful for research requiring frequent instrument relocation such as P-delay, micro-seismicity, aftershock and signal-to-noise ratio studies. The array unit combines the functions found in conventional fixed stations with a high degree of mobility. Conveniences such as solid state amplifiers, radio and clock circuitry, internal calibration, and minimum installation time are special features. With the battery supply provided, a one week period of unattended film and tape recording is possible. With commercial power, the instruments can operate unattended for up to sixty days. Useful magnification up to several million is available, depending on the frequency band selected.