[RUTHERFORD] EXISTENCE OF BODIES SMALLER THAN ATOMS 85 
velocity of light, while Kauffmann recently found that the velocity 
of some of the radium electrons was about 95 per cent of the velocity 
of light. ; 
Experiments of these very high speed carriers are of great import- 
ance at the present time, in order to throw some light on the question 
as to whether the mass of the electron is apparent or real. On the pres- 
ent electro-magnetic theory a rapidly moving charged body increases 
in apparent mass with increase in velocity. When the carriers travel 
with the velocity of light the apparent mass would be infinite. 
It is not yet settled what proportion of the apparent mass is 
electrical. It may possibly prove that the mass is altogether elec- 
trical in origin. If such should prove to be the case! (and it does 
not seem improbable), it would be very strong evidence in support 
of the view that all mass is electrical in character. 
It thus appears that electrons produced by the electric discharge, 
by a glowing carbon filament, and by ultra violet light, as well as those 
present in incandescent sodium vapour or spontaneously emitted by 
radioactive substances, all alike show about the same ratio of 
Since the charges are the same in each case, the masses must be the 
same for the electrons produced in such widely different ways. The 
electron thus appears to be the smallest definite unit of mass with 
which we are acquainted. The view has been put forward that all 
matter is composed of electrons. On such a view an atom of hydrogen 
for example is a very complicated structure consisting possibly of a 
thousand or more electrons. The various elements differ from one 
another in the number and arrangement of electrons, which compose 
the atom. 
We thus have a kind of modified Prout’s hypothesis in which the 
electron is the ultimate corpuscle of which all matter is composed. 
The physical existence of electrons is now accepted by many 
scientific men and there are a large number of prominent physicists 
who are developing mathematically the logical sequence of the idea. 
T need only mention a few of the more prominent workers—Drude, 
Voigt, Riecke in Germany, Lorentz and Zeeman in Holland, Poincaré 
and Becquerel in France, J. J. Thomson, Schuster, Lodge and Lord 
Kelvin in England, to show that the view has a solid basis of support 
among the ablest physicists. 

* Within the last month, important results bearing on this point have 
been published by Kaufmann and Abrahams. The former has shown that 
the apparent mass of the electron increases with the speed in the same way 
as the electromagnetic theory suggests. He has deduced that the apparent 
diameter of the electron is 10-13 cms, and that its mass is probably alto- 
gether electromagnetic in origin. 
