does 2. | 
za =4nD,, Au = 475, , 
dE, 4 OE, 
er PB Sym ene A (5) 
€, = Ane by — pz Des Ez = Ane d, + pr Dy, 
D'y = Dy Am Pe des H'z= Dz — ATM pe dys 
Dy = db, + My,» += dz + Mez. 
S 4. In LARMOR’s equations!) the velocity of translation yp, is 
represented by v, the sign a is used for those time-rates of variation, 
C 
d 
which I have indicated by a dot, and the sign a for the differential 
coefficients relating to a fixed point of space. Hence, in his notation, 
O d ij d 
_ =—=_ -_—- OS 
dt dt dx 
Rut et Op dp . 
If now, we write p instead of Ta, And Par an instead of 
d : : : 
= (p being any quantity, depending on place and time), and if 
besides we suppose the substance to be unmagnetizable, so that 
== 1, the equations of LARMOR become 
NE EKE dg +9) 
plees Scene” Sane 
opal : : d(h +h’) 
ae 1 Wee arn mk 
et 
ERR 0E dn ee 
Q=Aneig—ve , Rz=Anchtvb, 
B=b—4nvh , yee+4nnvg. 
These are the same as (5), as will be seen, if we replace 
Q, R, Js h, g's hj 
by 
€,, €, Dy: dz, My, Mz 
and 
b, 6, B+4nv(h+h), y—Anvlg Hg) 
by 
Dy Dz, Dy) Dz : 
Ile, p. 212 
