... His early works dealt with statistical methods especially in atmospheric, geomagnetic and ionospheric tides. In 1928, Bartels became professor in Eberswalde; in 1936, he became director of the Potsdam Geophysical Institute and full professor at Berlin university. ... With these statistical methods, he was able to disprove many widely accepted geophysical models on the one hand and develop some very useful and easy to apply geophysical indices on the other. ...