The photographs were taken with a small lens of only 2.5 CMS.
"Lectures on Stellar Statistics"
Carl Vilhelm Ludvig Charlier
The helium atom or alpha ray leaves the transforming atom with a velocity which varies in the different radioactive elements, but which is always very great, attaining as much as 2 x 109 CMS.
"The Birth-Time of the World and Other Scientific Essays"
J. (John) Joly
In the uranium family the fastest ray is 215 that of radium C. It attains 6.94 CMS.
"The Birth-Time of the World and Other Scientific Essays"
J. (John) Joly