Explosive harpoon
The explosive harpoon is a device used by whalemen to kill whales efficiently and without poison. As soon as the harpoon is thrown into the whale and fastened to it the wooden pin is broken by the power of the whale pulling upon the tow-line attached to the harpoon. This causes the fluke of the harpoon to open or turn upon the iron rivet, and the rivet will come in contact with the vial and break it, producing friction, cause the powder to explode.
History
The first explosive hand-darted harpoon patented in the United States was invented by Albert Moore of Hampden, Maine in 1844 (U.S. Patent No. 3,490, March 16, 1844). His harpoon, fashioned after the single-flued harpoon, had a single barb that pivoted on an iron pin. When the barb was closed, in the darting position, a small wood pin was inserted through holes drilled through the head and shank. A cavity in the single barb opened to the rear, and accepted a small glass vial of explosive which was held in place by a wood peg across the closing.
Today
In Norway, Japan, and Iceland, pentaerythritol tetranitrate is used in harpoon grenades. These are steel canisters that thread onto the tip of a reusable harpoon, and explode by means of a hook and trigger line when they have penetrated approximately half a meter into the whale. In Japan, unfortunately, their use has been shown to yield a poor rate of instantaneous kills (however still far more humane than a non-explosive "cold" harpoon), while in Norway which uses more advanced (yet expensive) grenades, 80% of whales are shot and killed instantly. Iceland uses the Norwegian grenades, which can kill even large fin whales instantaneously 84% of the time.[1]