Periodicity and new properties of the frequency curve. Bruno Hanisch uses the method of autocorrelation introduced by W. Pollack in geophysics for the discovery of periods in the frequency series of sunspots from 1794 to 1925. Dividing the whole interval into three sections he finds an eleven- and an eight-year period common to the three sections, whereas other periods found in the three sections differ widely from each other. The new method gives for the length of the main period II-8 years for the interval 1880 to 1925. This result agrees strikingly with the revolution period of Jupiter (Gerlands Beiträge zur Geophysik, 46, 1935).