Abstract
I. An experimental investigation using an acoustic interferometer with a magnetostriction source is described. Results on attenuation and velocity in tubes of radius 0.013 cm and upwards, from 10 to 20 kc/s, and for a variety of tube materials and gases are given. These confirm modified Kirchhoff's formulae.
II. The velocity and attenuation of plane sound waves in tubes of radius 0.02 cm have been measured in the transition region between adiabatic and isothermal flow.