A great, long, gray shape moved swiftly through the waters of the Thames. Smoke, pouring from three different points in the middle of this great shape, ascended, straight in the air some distance, then, caught by the wind, drifted westward. It was growing dark. Several hours before, this ocean greyhound-one of Great Britain's monster sea-fighters-had up-anchored and left her dock-where she had been undergoing slight repairs-heading eastward down the river.