1867 P. G. Tait tr. Helmholtz in London, Edinb. & Dublin Philos. Mag. 4th Ser. 33 491 We may..call the motions which have no velocity-potential, generally, vortex-motions.
1876 P. G. TaitLect. Recent Adv. in Physical Sci. xii. 290 The peculiar properties of vortex-motion were mathematically deduced..by Helmholtz.