P. N. BELIKOV. Speech and Hearing. Popular-Science Library of the State Publishing House. Moscow—Leningrad, 1927. Price 80 kopecks.

The range of questions touched upon by the author is considerably broader than one might think from the title. The booklet deals not only with questions of hearing and speech, i.e., physiolo-

…ical acoustics, but, in addition, the principal phenomena of the doctrine of sound, or physical acoustics, are set forth in systematic order.

The author presents the material in the light of the latest scientific achievements in acoustics and, moreover, uses examples to acquaint the reader with the most important technical applications of the doctrine of sound. As a result, the booklet is highly substantial; and since, in addition, it is entirely up to date, it will be of interest not only to the broad circle of readers for whom it is chiefly intended, but also to persons more closely interested in acoustics who have neither the time nor the opportunity to read the specialized literature.

I should note that the data given on p. 91 concerning the limit of audibility at 40,000 vibrations per second should be regarded as too high; according to the latest investigations of Lane, this limit lies no higher than 19,000 vibrations per second.

The booklet is written very vividly and engagingly, with the gift for popular exposition characteristic of the author.

S. Rzhevkin.