CONSTITUTION OF THE ATOM—EVE. 191 
(negative) as 1:1800, for that is the ratio of their masses, while their 
charges are equal and opposite. Hence we have 
Mass. Diameter, 
Cm. 
UAEOM es cee setae eee ain cies b caon seine Seen eaten se oSulewoescucteceeteuance 1 10-8 
INerativelclectronmepceeas es soais> cae Seon reson ee meron sso sanice cena ewen ues 1/1800 19713 
if 
IROSitive elechromepe eeeert eats enc are Sees Heer nae pee cine dois waw ckijecuetsemees 19-16 
Rutherford cautiously remarks that there is no experimental evi- 
dence against such a supposition. 
Those who wish to follow the matter deeper must refer to many 
articles in the Philosophical Magazine, several letters to Nature, 
Soddy’s ‘‘Chemistry of the Radio-elements,’’ Part II, and Perrin’s 
“Les Atomes.”’ The chief writers have been Rutherford, W. H. 
Bragg, W. L. Bragg, G. C. Darwin, Moseley, Broek, Bohr, Russell, 
Fajans, Soddy, Hevesy, Nicholson, and Marsden. 
Much has yet to be done, and much to be revised, but that the first 
great forward strides have been taken in the right direction there can 
be little doubt. 
