A median section through the earth showing composition of the interior and
transmission of earthquake waves. In: Earthquakes and Astronomy" by N. H.
Heck. Published in: The Sky, March 1937. P. 14.
Image ID: cgs02177, NOAA's Historic Coast & Geodetic Survey (C&GS) Collection Photo Date: 1937 Credit: Collected Papers of Captain Nicholas Heck, NOAA Central Library
Category: Coast and Geodetic Survey/Geophysics Seismology/
