Designed to provide compressed or rarified air and based on the theories of Waldenburg. From Von Ziemssen’s Handbook of General Therapeutics, Volume 3, published by Smith, Elder, 1885, page 410.
“Weil at Berlin has constructed a serviceable double apparatus (fig. 23), by connecting two Waldenburg’s apparatus inferiorly bu a short india rubber tube, so that while one cylinder sinks the other rises, and conversely, so that one is ready for use as soon as the other has ceased to act. The apparatus was not designed with the object of an alternating respiration, but, as in the one afterwards invented by Schnitzler, in order to be able to employ compressed or rarified air uninterruptedly.”