One of the most.destructive weapons introduced in the war of 1940 is the multiple incendiary bomb dumped over the wooden cities of Finland from Russian planes. The secret of its operation was learned when Finnish soldiers. captured an unexploded bomb. Seven and one-half feet long and two and one-half feet thick, it had projecting vanes which made it spin as it fell, and as it rotated sixty small incendiary bombs sprayed out in all directions, starting fires over a wide area.