Ultrasonic Doppler for distance measurement [Correspondence]

The above-named paper [ibid., vol. UE-8, pp. 6-13, March, 1961] recently came to the attention of the author who made an error analysis of a similar proposed distance measurement scheme during the latter portion of 1958. The purpose of this communication is to call attention to an apparent misstatement in Wachspress and to present some supplementary information on this subject.