As to material, Admiral Jellicoe notes the superiority of the German fleet in range-finding devices, searchlights, smoke screens, a star shell--unknown to the British and invaluable for night fighting--and in the armor piercing quality of the shells. Moreover the Germans were completely equipped with systems of director firing, while the British were not. According to Admiral Sir Percy Scott,[1] "at the Battle of Jutland ... the commander in chief had only six ships of his fleet completely fitted with director firing ... he had not a single cruiser in the fleet fitted for director firing." [Footnote 1: FIFTY YEARS IN THE ROYAL NAVY, p. 278.] The greatest superiority of all probably lay in the structural features of the newer German ships. For some years prior to the war Admiral von Tirpitz had devoted himself to the problem of under water protection, to localize the effect of torpedo and mine on the hull of a ship. To quote the words of von Tirpitz:[2] [Footnote 2: MY MEMOIRS, Vol. I, p. 171.] "We built a section of a modern ship by itself and carried out experimental explosions on it with torpedo heads, carefully testing the result every time. We tested the possibility of weakening the force of the explosion by letting the explosive gases burst in empty compartments without meeting any resistance. We ascertained the most suitable steel for the different structural parts, and found further that the effect of the explosion was nullified if we compelled it to pulverize coal in any considerable quantity. This resulted in a special arrangement of the coal bunkers. We were then able to meet the force of the explosion ... by a strong, carefully constructed steel wall which finally secured the safety of the interior of the ship."