From “Methods in pulmonary physiology”, by Bertels H, Bucherl E, Hertz CW, Rodewald G, Schwab M. Translated by Workman JM. Hafner Publishing Co., 1963, page 103.
“This ergometer works on the same principle as that of Benedict. Her also braking is applied to a rotating metal disc by a variable magnetic field. Work can be done either on footpedals or a crank. An advantageous feature is the taking over the start of work by an electric motor which switches itself off automatically.”