Tonometers are secondary frequency standards, and often consist of a series of cicular cylinders suspended by light cords from their two nodal points. The frequency is inversely proportional to the square root of the length, which enables the higher frequency rods to be machined to the right lengths. This set of tonometer bars was made by the Standard Scientific Company of New York and is in the collection of the Physics Department at the University of Texas. It  probably dates from the first quarter of the twentith century. Other tonometers can be found with the Rudolf Koenig aparatus.

 Return to Acoustics Home Page | Return to Home Page