Pair of Tuning Forks In A Resonance Box

For demonstrating the production of beat frequencies. Comprises two nickel plated forks A (426.6) mounted on individual boxes. One fork is provided with adjustable mass by means of which frequency may be shifted from the nominal 426.6 When both forks are sounded a clearly audible 'beat' is produced, its rate depending upon the difference in frequency between the forks.