=3 ) 
have proved to be successful techniques which yield important data in the 
Arctic Oceane New instruments were adapted or developed for this station. 
These included a microbarovariograph to record small air pressure oscillations, 
a precision depth recorder for continuous sounding, a nuclear precession 
magnetometer for the total magnetic vector, a long period seismometer for 
detection of earthquakes and ice motion. This program was continued until 
the evacuation of Station Charlie in January, 1960. 
During the spring of 1960, a program of seismic refraction 
measurements was executed at T-3. A seismic spread was placed on the ice 
near the ice island and shots were fired at varying distances, Transportation 
was by the Cessna airplanes from Arctic Research Laboratory and by Weasel 
tracked vehicle. Some ice tremor studies were also made. The work at T-3 
was continued again in the fall with the installation of a microbarovariograph , 
a puclear precession magnetometer and a long period seismograph. 
