The first memory drum.

For most of the 20th century, the memory drum was the standard American apparatus for memory research. The first memory drum dates from 1887 in the work of G. E. Müller and Frederich Schumann, and an illustration of their device appeared 16 years later. This device apparently was invented to resolve the difficulties created by Ebbinghaus's method. The memory drum was a kymograph used to control the display of learning materials. Cattell used something similar for his dissertation with Wundt, though not for verbal material. From Müller's writings, images of this device and kymographs contemporary to Müller's innovation, characteristics, aspects, and difficulties of the development of this drum are presented in the context of its use to resolve the difficulties created by Ebbinghaus's method. An improved device was offered by instrument makers Diederichs in G?ttingen and Zimmermann in Leipzig, both in 1894. Surprisingly, from 1903 Zimmermann offered only the original, unimproved device, mistakenly portraying it as appropriate for paired-associate learning procedures.