2T = Ap2 + Bq2 + Cr2 − 2Fqr − 2Grp − 2Hpq.

(5)

Again, if x, y, z be the co-ordinates of P, the component velocities of m are

qz − ry,   rx − pz,   py − qx,

(6)

by § 7 (5); hence, if λ, μ, ν be now used to denote the component angular momenta about the co-ordinate axes, we have λ = Σ {m (py − qx)y − m(rx − pz) z }, with two similar formulae, or

λ =  Ap −Hq − Gr = ∂T,
∂p
μ = −Hp + Bq − Fr = ∂T,
∂q
ν = −Gp − Fq + Cr = ∂T.
∂r

(7)