370 PHYSICS: H. BATEUAN 
+ 12 (i> • V') [v-{bX gO] + 6 (v V) [v' ■ (g' X gO] + 3v'' [v ■ (g' X gO] 
+ i{v v') [v' ■ (b X go)] + 2v'' [v- (bX &)] + 2 {vv') Iv" ■ {g' X go)] 
+ 2{v v") [v' ■ (g' X go)] + 2(v'- V") [v ■ (g' X go)] + - -v") [v"-{g X go)] 
+ i [v {gX go)] + J ^" W ■ (g' X go)] + ^ (»' • V") [v' ■ (g X go)] 
+ 1 V" b>"- (gXgo)] + ^ ^P^^ {6{v v'Y [v ■ {g'XgO] + 4 (J< • v'Y [v ■ {bXgo)] 
+ 4 (z; • d') iv- v'O [v ' {g'X go)] + l(v' v")' [v • (gXgo)] + ^ v'^v • v^) [v'- (gXgo)] 
+ ^ • X ^o)] -h-^iv vy [v'^ '(gXgo)]+-^iv' V') {V • ^'0 • {g X ^)] 
'\- {v'v') {v' 'v"){v'{gX g,)] ■\- ^- V'' {v'v")[v'{gX go)] 
+ ^ tP^. 1 24 (z; • v'f [v • {g' X go)] ^ n {v - {v ■ v") [v {gX go)] 
6{v'v')^[v' ■ {gX go)] -\- 9 v'^ {V ' v')^[v • {gX go)]] 
, 288 13c2+z;2 
3. In the special case of a magneton of charge ^ire and moment 
47r^ describing a circular orbit at a constant speed and in such a way 
that the axis of the magneton is always perpendicular to the plane of 
the orbit, we find that if k is constant the rate of radiation of energy is 
- TTce^ + - TTC^ek -\ irck^ - 
3 (c2-z;2)2 3 z;(c2-z;2)3 15 ^2 2(c2-2;2)4 
If e, V and are given the minimum value of this positive quantity is 
found to be 
27r ce'v'^ c^+4v^ 
T (c2-?;2)2 2^2+3^2 
and is thus about | of the rate of radiation from the electric charge alone. 
Some years ago Dr. W. F. G. Swann expressed to me the desirability of 
calculating the radiation from an electron which rotates about its axis 
like a planet while describing a circular orbit. If such an electron 
can be treated as a magneton to a first approximation the above result 
is applicable. The fact that the radiation is reduced by rotation may 
indicate that revolving electrons do rotate. 
