Many had tried to solve the problem of an electric pump, but generally they came to grief owing to the current short-circuiting in the water. Macdonald worked at the problem until he succeeded in overcoming it, and the result was a drum-like pump with the inner parts spinning at a high speed and forcing the water upwards through the pipe. Instead of fixing his pump at the top end of a suction pipe, Macdonald placed his pump at the bottom end of a pipe and dropped it into the water. The pump weighed about half a ton, and owing to the fact that it worked entirely under water, with water flowing all round and through its bearings, it was not liable to suffer loss of efficiency through air leakage. The tendency of the pump to overheat owing to the speed at which it worked was checked by the cold sea water always passing through it. It was, in effect, a water-cooled pump that was excellent for working at depths a little beyond the reach of the ordinary pump. [Illustration: THREE OF THE ELECTRIC PUMPS WHICH PROVED THEIR EFFICIENCY DURING THE WAR. THEY REMAINED IN THE HOLD OF THE SUNKEN WESTMORELAND FOR THREE MONTHS UNTIL SHE WAS RAISED. WORTH £3,000,000, SHE WAS BY FAR THE RICHEST SALVAGE PRIZE OF THE WHOLE WAR] For touch-and-go cases the submersible pump was much in demand by salvage officers, but for cases that required long and steady pumping for days and perhaps weeks the wonderful Gwynne pumps were not to be excelled. Their extraordinary reliability is marvellous. So long as you give them the steam to work with, coupled with proper attention, they will do almost anything that you ask of them. They will pump steadily for days and even weeks without stopping, throwing overboard the specified number of tons of water an hour. They are, indeed, among the mechanical marvels of the age, practically as perfect as any machine is ever likely to be. [Illustration: THE DAMAGE WROUGHT BY A GERMAN TORPEDO. A GOOD IDEA OF THE IMMENSITY OF THE HOLE MAY BE GAINED BY COMPARING IT WITH THE LEGS OF THE MAN STANDING ON THE SCAFFOLDING IN THE WRECKED ENGINE ROOM. DESPITE THE DAMAGE, THE SHIP WAS SAVED] So sure are they, that salvage men will willingly put to sea in a badly leaking ship and set out on a voyage that may last a week or two. If the pumps stopped, the ship might founder in two or three hours. The men know it, but they do not worry. They have implicit faith in the pump, and although merely the power of the pump stands between them and death they carry on quite unconcerned. And while the water is finding its way into the breaches in the hull of their ship the pumps are steadily throwing it over the side. As Henry Ensor, one of the cleverest salvage experts alive, once remarked to me: “For a long voyage in a leaking ship, give me the Gwynne.”