a missile instrument of the Australian aborigines, with which they are said to be very dexterous in hitting birds. It consists of a piece of hard wood, with the curve of a parabola, and is about 2 feet long, 2½ inches broad, ½ inch thick, and rounded at the extremities. One side is flat, the other is rounded, and it is brought to a bluntish edge. It is discharged with the hand by one end, the convex edge being forward and the flat side upwards. After advancing some distance, and ascending slowly in the air with a quick rotary motion, it begins to retrograde, and finally falls to the ground behind the projector. The principle of the boomerang has been attempted to be applied to the propulsion of ships. See Steam Navigation.