THE PHILIPPINE 
JOURNAL OF SCIENCE 
VoL. 18 APRIL, 1921 No. 4 
THE STRUCTURE OF THE ELECTRON '* 
By GRANVILLE A. PERKINS 
Of the Bureau of Science, Manila 
The general advances during the last twenty years in scientific 
knowledge concerning the properties of matter have been con- 
nected intimately with the unit of negative electricity, called 
the electron. Although the unitary nature of electricity was 
strongly suspected by Faraday, and others since his time, on 
the basis of electrochemical evidence, the conclusive demon- 
stration of this is of comparatively recent date. The discovery * 
that cathode rays act as if they consist of negatively charged 
matter moving with about one-tenth the speed of light and show 
a nearly constant ratio of charge to mass, as would be expected 
of a stream of negative units, was soon followed by the develop- 
ment of methods* by which these particles have been caught 
in cloud drops of water and of oil. In this manner not only 
has the discrete nature of negative electricity been proved, but 
the elementary charge has been exactly measured‘ and found 
to be 4.774 x 10° of the customary electrostatic units. 
*Rearranged from an address before the Freer Club, Manila. Received 
for publication April 15, 1921. 
*Thompson, J. J., Phil. Mag. V 44 (1897) 298; Wiechert, E., Verhandl. 
der Physik.-Okon. Gesellsch. zu Kénigsberg, i. Pr. (1897). 
* Wilson, C. T. R., Proc. Roy. Soc. March 19, 1896; Phil. Trans. Roy. 
Soc. A 192 (1899) 403; Thompson, J. J., Phil. Mag. V 46 (1898) 528; 
Wilson, H. A., Phil. Mag. VI 5 (1903) 429; Millikan, R. A., Phil. Mag. 
VI 19 (1910) 209. 
‘Millikan, R. A., Science 45 (1917) 327. 
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