Orig. bildtext... TO MEASURE VELOCITY OF EARTHQUAKE WAVES. Cambridge, Mass. - Dr. L. Don Leet, Harvard University, who is directing research work of the Geology Department of the University which will this summer try to determine the substance and measurement of the earth by a series of dynamite explosions. By these man-made earthquakes, it is hoped to measure the velocities of earthquake waves through granite in an attempt to prove that the shell of all continents are granite base. Dr. Leet is one of the world's best known seismologists and is shown here with the three component portable seismograph built specially for this research work. Anm. Seismografer Mätinstrument persons: L. DON LEET sites: BOSTON ;USA