
Structure of the Atom. 259 
the axis of x; then the number of corpuscles represented by 
OP, will be arranged like the 60 corpuscles with an addition 
ring of Q, P; corpuscles (fig.2). To find the next member of the 
family, draw (QP, par allel to QP, cutting the axis of xin P,, 
then OP, will represent the muitiber of eor puscles in the next 
member of the family; and by continuing the process we 
ean find the successive members. Thus we see that we can 
divide the various groups of atoms into series such that each 
member of the series is derived from the preceding member 
(2. e. the member next below it in atomic weight) by adding 
to it another ring of corpuscles. We should expect the 
atoms formed by a series of corpuscles of this kind to have 
many points of resemblance. ‘Take, for example, the vibra- 
tions of the corpuscles; these may be divided into two 
sets :—(1) ‘Those arising from the rotation of the corpuscles 
around their orbits : if all the corpuscles in one atom have the 
same angular velocity, the frequency of the vibrations pro- 
duced by the rotation of the ring of corpuscles is proportional 
to the number of corpuscles in the ring; and thus im the 
spectrum of each element in the series there would be a series 
of frequencies bearing the same ratio to each other, the ratio 
ef the frequencies being the ratios of the numbers in the 
various rings. 
The second system of vibrations are those arising from the 
displacement of the ring from its circular figure. Ifnow the 
distance of a corpuscle in the outer ring from a corpuscle in 
the collection of rings inside it is oreat compared with the 
distance of the second corpuscle from its nearest neighbour 
on its own ring, the effect of the outer ring of corpuscles on 
the inner set of rings will only “disturb” the vibrations of 
the latter without fundamentally altering the character ot 
their vibrations. Thus for these vibrations, as well as for 
those due to the rotations, the sequence of frequencies would 
present much the same features for the various elements in 
the series; there would be in the spectrum corresponding 
groups of associated lines. We regard a series of atoms 
formed in this way, 7. e. when the atom of the pth member is 
formed from that of the (p—1)th by the addition ofa single 
ring of corpuscles, as belonging to elements in the same group 
in the ar rangement F the elements according to the periodic 
law ; 7. e. , they form a series which, if arranged according to 
Mendeléef’ s table, would all be in the same vertical column. 
The gradual change in the properties of the elements which 
takes place as we travel along one of the horizontal rows in 
Mendeléef’s arrangement of the elements, is also illustrated by 
the properties possessed by these groups of corpuscles. Thus 
