Excerpt from Progressive Medicine, Vol. 4: A Quarterly Digest of Advances, Discoveries and Improvements in the Medical and Surgical Sciences; December, 1900 Its principle is based upon a valve arrangement. The apparatus con sists of a rubber tube, not too flexible (thickness, three-eighths of an inch; length, twenty-six inches), at the end of which a hard-rubber capsule is attached (fig. 1, The latter contains numerous very small openings all around, and one very large opening at its lower extremity. Within the capsule, which can be unscrewed, lies a small aluminium ball. This moves easily and freely within the capsule, and when it lies above the lower opening it entirely occludes the same. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.