Smoke Trail As S.O.S. -- The smoke emitted from the canister increases in density, until it can be seen for over thirty miles.A new life-saving apparatus has been designed for seagoing craft in the shape of a smoke trail. By pressing a trigger on a small canister, a cloud of orange smoke is released which will rise for an hour or more, increasing in density. Ministry of Shipping experts have tested this invention in secret and it has been proved that this smoke can be seen more than 30 miles away. Ship-wrecked men will be able to use this device as a very effective S.O.S. October 16, 1941. (Photo by Fox Photos).