Excerpt from Papers and Proceedings of the Royal Society of Tasmania for the Year 1913 Where k is a constant. W. Wilson has shown (proc. Roy. Soc., vol. 85, p. 240) that the law represented by equation (1) holds also for the fi rays given out by radium. These rays had a velocity as high as 29 x 1010 cm. Per second. The cathode rays I used had velocities as low as 3 x 109 cm. Per second. So that the law (i) holds over a consider able range of velocities. From data given in my paper, it is easy to calculate the constant If. One cathode ray moving With a speed of 48 x 109 cm. Per second makes 15 pairs of ions per cm. Of air at a pressure of 1 m.m. Of mercury. 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.