(4)
the equations of motion (4), (5), (6) § 24 can be written
| dK | − 2uζ + 2wη − | d(ψ,m) | = 0, ..., ...; |
| dx | d(x,t) |
(5)
and therefore
| ξ | dK | + η | dK | + ζ | dK | = 0. |
| dx | dy | dz |
(6)
Equation (5) becomes, by a rearrangement,
| dK | − | dψ | ( | dm | + u | dm | + v | dm | + w | dm | ) |
| dx | dx | dt | dx | dy | dz |
| + | dm | ( | dψ | + u | dψ | + v | dψ | + w | dψ | ) = 0, ..., ..., |
| dx | dt | dx | dy | dz |