Few people know that such wonderful ropes exist, but the salvage expert has full knowledge of where to get them when he requires them, as he did in the case of the _Silurus_. The ropes were all fixed in place on the edge of the Gareloch, two batteries of boilers were set up to supply the power, but before they could be used it was necessary to arrange a series of signals owing to the fact that the boilers were out of sight of each other. For one lot to haul faster than the other would have been fatal. It was absolutely essential that each rope took its share of the load and that all were hauled on at the same time. As showing how carefully everything must be considered in so important a case, the salvors even worked out how much efficiency they would lose through friction when hauling on the ropes. They left nothing at all to chance. Giant wire ropes were lashed round some of the top gear to prevent it breaking away when the ship came over, a big trench was cut for one set of ropes to work in, as only by cutting the trench was it possible here to get a direct pull on the ship, and at last the signal was given to haul away. Slowly the _Silurus_ came up, her funnel was tugged from beneath 10 feet of mud. The hauling went on until the pontoons were clear of the water, until they were no longer a help but a hindrance, so the salvors cut through the wire lashings with blowpipes and freed them from the ship. Adjustments were made and the next haul set the _Silurus_ on a fairly even keel. Despite the strain to which she had been subjected, the salvor made all his calculations so carefully that she was not in the least damaged by the operations. Over £56,000 was spent by the salvor on these operations, but he won his tug-of-war with flying colours, and the award he received was the reward of sheer merit. As already mentioned, the divers used hacksaws to cut holes in the hull under water. In other cases they may bring into play a range of pneumatic tools--hammers, chisels, and drills worked by compressed air, which is pumped through a pipe from a boat on the surface. The hammer and chisel will deliver hundreds of blows a minute, each blow doing an almost imperceptible amount of work, but the hundreds of blows tell in the end. An air-driven drill, in spite of the disadvantages of working under water, will cut a hole an inch in diameter through a plate or girder an inch thick in one minute. Frequently, it is desired to remove some submerged rock which interferes with navigation, and for this purpose pneumatic drills are often brought into play to make the holes for the charges of dynamite. The diver proceeds by drilling a series of holes, inserting his cartridges, after which he stops up the top of the hole with a special stopping in order to drive the force of the explosion downward. Then he withdraws to the surface and the boat removes to a distance before the dynamite is exploded.