In 1924, the German psychiatrist Hans Berger connected a couple of electrodes (small round discs of metal) to a patient's scalp and detected a small current by using a ballistic galvanometer. During the years 1929–1938 he published 14 reports about his studies of EEGs, and much of our modern knowledge of the subject, especially in the middle frequencies, is due to his research. Berger analyzed EEGs qualitatively, but in 1932 G. Dietsch applied Fourier analysis to seven records of EEG and became the first researcher of what later is called QEEG (quantitative EEG).