Book Description

Excerpt from The Archives of Internal Medicine, 1913, Vol. 12 As in our method for determining the blood-flow to the arm, the latter was enclosed in an air plethysmograph which was connected by air transmission with an apparatus which recorded the changes in arm volume. In order to obtain records of the average blood-flow to the arm, any form of volume recorder may be used. We early used the bellows volume recorder of Brodie for this purpose, but more recently we have used a bell recorder similar to that employed for recording respiratory movements. To obtain accurate records of the flow during each portion of the pulse cycle, however, a more sensitive recorder becomes necessary. In a series of exhaustive researches, 0. Frank2 has discussed the necessary requisites of a recorder which shall follow sudden changes in movement with accuracy. The most important of these requisites is that the apparatus itself should possess a rapid rate of inherent vibration. A slow rate of inherent vibration indicates that the apparatus will not follow sudden changes in movement accurately and that the vibrations of the apparatus markedly deform the tracings. With a rate of inherent Vibration which is very rapid relative to the changes in movement to be recorded, the latter are recorded much more accurately, and the vibrations of the instrument can be easily recognized should they appear on the tracings. We have, therefore, endeavored to employ an apparatus which should have as rapid an oscillation time as possible. The following formula furnishes an approximate idea of the factors affecting the time of a single oscillation T In a system similar to that which we have employed. 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.