Sometimes, however, when it is desired to deepen a rocky channel, a powerful rock-cutter weighing several tons is brought into play. This tool is shaped like a pencil and the nose is fitted with a specially hardened cutter. It is raised to a height and allowed to drop upon the rock, which it gradually pulverizes and breaks up, the rock-dredger coming along and completing the work. Another method followed in the deepening of the channel of the Clyde was to use diamond drills for boring the holes for the explosives. The famous Enderslie Rock which caused all the trouble was revealed one day about the middle of the nineteenth century through the keel of a steamer coming into contact with it. Up till that time nobody knew of its existence, but when this steamer damaged herself the authorities started investigations. They found a bed of rock just over 900 feet long by 320 feet wide, which menaced the bigger ships that were beginning to navigate the river. The only way of making shipping safe was to deepen the channel by removing the rock. Accordingly it was attacked by men working in a diving bell who began blasting it away with gunpowder. By 1869, after working on it for five years and spending £16,000, half the channel was deepened to 14 feet, the other half remaining at 8 feet. Eleven years later the rock was again attacked, this time by diamond drills worked by steam-engines. Five years of continuous work saw the rock removed to a depth of 20 feet over the whole channel. This improvement, which entailed the blasting away of over 100,000 tons of rock, cost £70,000, so the Enderslie Rock, upon which the Clyde authorities spent in all a sum of £86,000, proved rather an expensive obstruction to find in the river. But it was no mean feat to remove it, as was done, without in any way interfering with the traffic. CHAPTER XV There have been few pluckier fights for a ship than that waged over a great, camouflaged merchantman torpedoed by the Germans off the Cornish coast during the war. She was badly holed, but her captain bravely stuck to her and managed to beach her near Bude. Hastening to her aid, the salvage officer found her on a beach exposed to the full force of the Atlantic. With wind and sea rapidly rising, it was obvious that nothing could prevent her from going to pieces. The rollers were battering her, shaking and straining her ominously, seeking to finish what the German torpedo had begun.