IN the course of some experiments preparatory to a lecture on vortex rings, I have introduced certain modifications which may be of interest to teachers and students of science.

These Vortex Hunter Rings position the center of the riflescope tube at a height of 0.87 inches (22.0 mm) from the base. Mounting to a Picatinny or Weaver type rail, the standard, 2-screw Hunter ...

The central part of the disc thus formed soon disappears, and consequently a ring form results. This is a very slowly whirling vortex ring. As it proceeds, the radius of the ring is augmented ...

These Vortex Hunter Rings position the center of the riflescope tube at a height of 0.87 inches (22.0 mm) from the base. Mounting to a Picatinny or Weaver type rail, the standard, 2-screw Hunter ...