Abstract
The apparatus is suitable for measuring at surface strains up to 10-3. The major contribution to extraneous losses is the aerodynamic damping, even at pressures as low as 10-6 Torr. It has been shown that for free molecule flow, the aerodynamic damping is directly proportional to the pressure, but the constant of proportionality predicted is at least 28% less than that obtained experimentally, the discrepancy not yet being explicable. However, the experimental value may be used in practice so as to allow for aerodynamic losses. It is not necessary to use very low pressures if only the fibre modulus is required.