Earthquake waves as they proceed over the earth's surface radiate sound waves into the atmosphere. Several instances of such sound waves have been observed at Washington, D. C. A notable instance was the great Montana earthquake of August 18, 1959 (UT). Calibrated microphones responding to very low frequencies measured the amount of the radiated sound pressure and the time delays between sound pressures at several geographic locations. From these have been deduced the vertical amplitudes of the seismic waves and their speed of transit through the Washington area. Recordings of the waves will be presented. Results of the acoustical measurements will be compared with seismological observations. With respect to one of the Chilean earthquakes, sound radiated at the epicenter was apparently propagated through the atmosphere to Washington.