Device used for laying fishing nets for ice fishing, apparently invented by an anonymous fisherman-cum-blacksmith in Manitoba in 1912. This ingenious contraption solved the problem of getting the other end of the net from point (fishing hole) A to point B underneath the ice, vastly improving the haul compared to what you could catch with only a line through a hole.
The jigger is a wooden plank approximately 6 feet in length. In the middle there's a slit with an arm that's hinged to a rod. It's inserted through a hole in the ice with a line attached to the rod. By tugging on the line the rod is made to move and drives the arm upwards and backwards, making it bite into the bottom of the ice and, using this for leverage, the jigger creeps forward.
A second person follows it above the ice listening for the scratching sound it makes in order to establish its location. After it's moved a net's length, another hole is drilled in the ice and the line and jigger are recovered. The first person, who was operating the jigger, can now attach the net to the line and pay it out while the second person pulls at the line until he gets the other end of the net which is now strung beneath the ice. All they have to do now is come back later and haul in the net for instant frozen fish.