This is the housing for a vibrating string acceleromer, This device is based on the fact that the frequency of a vibrating string is proportional to the suspended mass. A current passed through a wire in the presence of the magnetic field causes the wire to vibrate at its resonant frequency like a violin string. Special circuitry then measures the change in vibrating frequency due to the change in weight and thus acceleration.This is a miniaturized version of the instrument originally developed for use in ICBM's. It served as the prototype for an accelerometer used by Apollo 17 astronauts to measure the Moon's gravity. Dr. Alexander Voutas, its inventor, donated it to the Museum.