/
, approaches 107 electromagnetic units, and
a value of 1.6 x 1010 cm/sec. These values are of the same order of magnitude as for the cathode rays.
Kaufmann has made exact experiments on the same subject. This physicist subjected a very narrow pencil of radium rays to the simultaneous action of a magnetic and an electric field, both fields being uniform and acting normal to the primary direction of the pencil. The pencil is received upon a photographic plate placed perpendicular to its initial direction. In the absence of the two fields the impression on the plate is a small circular disk, almost like a point. When the magnetic field acts alone the different β-rays are unequally deflected but remain in a plane normal to the field, producing upon the plate an impression in the form of a straight line. When the electric field acts alone the different β-rays are unequally deflected in a plane passing through the field and producing upon the plate an impression which is a straight line perpendicular to the one preceding. When both fields act simultaneously the impression on the plate is a curve. Each point of the curve corresponds to a different kind of β-ray. Taking as axes of coordinates on the plate the straight lines obtained when each of the two fields acts alone, the coordinates of each point of the curve represent the relative magnetic and electric deviations for each kind of ray.
The following are the figures for
and
