This illustration is from Fahrrad & Radfahrer by Wilhelm Wolf published, 1890 in Leipzig (reprinted in 1988 by Harenberg, ISBN 3-88379-106-1):
According to the description in the above text, the inventor was a certain Mr. Vietor from Osnabrück. It is stated that this kind of mechanism will allow the legs to move naturally as in walking. The following illustration, from the same source, indicates that apparently this was really the intention, with the "rider" almost standing upright in the pedals: