Now this is just what a vortex-ring would do in an incompressible frictionless fluid.
The Unseen World and Other Essays|John Fiske
A vortex-ring produced in the air behaves in the most surprising manner.
The Machinery of the Universe|Amos Emerson Dolbear
One may, without mechanical difficulties, imagine a vortex-ring destroyed.
The Machinery of the Universe|Amos Emerson Dolbear
Through a vortex-ring or tube, the fluid circulates in closed lines of flow, each one of which is laced through the tube.
Lord Kelvin|Andrew Gray
This vortex-ring theory shows easily how possible it is to-day to think what once was philosophically incredible.
The Machinery of the Universe|Amos Emerson Dolbear
vortex ring
noun
a stable perturbation in a fluid that takes the form of a torus in which the flow rotates in the section of the torus so that the pressure difference between the inside and outside of the torus balances body forces. The best-known vortex ring is a smoke ring