2e58 
Proceedings of the Royal Physical Society. 
Now 
d{b'X:,) dihic^c) dihie,) 
— u + — 7 — - V + — 7— lU = 
ax ay az 
<£)"'(t)-<t) 
W 
and therefore the expression on the left hand side is of the 
second order in u v w, and may therefore be neglected. 
Hence the resultant action Sbt x -{■ u, y z + w, parallel 
to the axis of x, due to the material molecules in motion, 
d'TCx d^x dvr 
and 
Similar expressions may be found for the resultant actions 
parallel to the axes of y and z. 
The action on the particle of ether a.t x + u, y + v, z w, 
parallel to the axis of x, due to the etherial medium when 
in motion, may, by analogy from (2.), be expressed in the 
form 
d<px d<px d(px , 
+ + d^^^ + W 
and 
n^/^ ^ dK""' ^i""^] 
Hence, adding (2.) and (4.), and recollecting that Tx + <Px=^7 
we have for the motion of the ether the equations 
d^u d(px d(px d<px 
d^x d'^'x d'TTx ^ 
= similar expression, involving cr^, and <py 
= similar expression, involving ^r, and <f>, 
