LEET DISCUSSES SEISMOGRAPHY OF RECENT TREMORS

Records taken at the Harvard Seismology Station during the recent earthquake at New Zealand, which resulted in many deaths and unprecedented damage, were explained yesterday by L. D. Leet, instructor in Seismology, and director of the station. The earthquake, which occurred last Tuesday night, was recorded the previous evening at 6.06 o'clock by the University seismograph machines.

This discrepancy in time is explained by the fact that New Zealand is 9,000 miles to the east, of Cambridge. The distance was traversed by tremors passing 1,800 miles beneath the earth's outer crust, in 19 1-4 minutes, which registered a displacement of one thousandth of an inch on the seismograph machine. Dr. Leet regards it as a curious coincidence that on Monday, June 16, 1930, the record of a disturbance coming from the same locality was registered at a time only 69 seconds earlier than the recent earthquake.

Leet to Investigate

This summer Dr. Leet will make extensive investigation as to the nature of the foundations of the earth. With two portable seismographs recently acquired by the station, he will make use of the tremors caused by explosives to measure the degrees of vibration registered by granite under varying degrees of pressure.

The instrument used will be a commercial one developed for determining the existence of oil deposits, and one more highly specialized, unique in the history of the science, perfected by H. G. Taylor, of Washington. Dr. Leet will conduct a course in the use of these instruments, which will begin the second half year. Under the name of Geology 6, it will deal with the study of seismography and seismic prospecting, a course which has never before been given at Harvard, for lack of the proper instruments.