THE ninth number in the new series of the publications of the Austrian Academy of Sciences relates to earthquakes observed during the year 1901 in Lemberg. The first feature which one observes in this publication, the author of which is Dr. W. Laska, is that he describes each earthquake according to the phases it exhibits, the various phases being distinguished from each other by differences in their periods. Twenty years ago, earthquakes were described as consisting of preliminary tremors, shocks and concluding vibrations, each of which had distinguishing periodic motions. Now we find first preliminary tremors of types pxf and, second preliminary tremors of types p2′, p2″, P2″ and P″ and on they go, commencing with, with periods between 2.1 and 6′9 seconds, and ending with types where the periods have exceeded one minute. Inasmuch as these groups overlap, so that it is frequently difficult to assign a set of waves to their proper group, for our own part we are for the present content to divide the seismic spectrum into four parts-first and second preliminary tremors, large waves and concluding vibrations. In addition to these entries, Dr. Laska gives tables of tri-daily readings of two levels and of a thermometer. The most interesting portion of the work is, however, found in its introduction, where, amongst other matters, reference is made to the natural period of a pendulum as influencing the magnitude of its records and to rules which enable an observer to determine the distance of an origin from the inspection of a seismogram.
"Publications of the Earthquake Investigation Committee in Foreign Languages," No. 5, pp. 71–80. (Tokio, 1901.)
Jour. Sc. Coll., Tokio, vol. xi., p. 158.