DEFENCES AGAINST OFFENSIVE TORPEDOES.
Vessels at anchor in protecting themselves against torpedoes establish three separate lines of defence. The outer line consists of guard-boats; the boats of the ship, either carrying machine and boat guns or having their crews armed with rifles, patrolling the approaches to the ship at such a radius as may be well guarded by the number of boats employed. The second line consists of a boom of logs or spars arranged around the ship at a distance of from twenty to fifty feet, having in addition, wherever practicable, heavy nets which hang down below the level of the keel. The third and inner line consists of the machine-guns and small-arms of the crew, the double hull and compartment construction of the vessel itself, and powerful electric lights which at intervals sweep the water in the vicinity of the vessel, lighting up every approaching object.