The form of the lightship varies according to its locality: in Ireland the hull is more elongated than in England; but in all cases the object to be attained is the same—resistance to the force of the winds and waves. It is desired that in the most violent tides, in the midst of the angriest billows, and in situations the most exposed to the influence of the currents, it shall drag as little as possible upon its anchor. That it may at all times and in all conditions preserve the same maritime position, it is securely moored. Like a galley-slave, riveted to an iron chain, it can move neither to the right nor to the left. The length of its cable is, of course, regulated by circumstances: at the Seven Stones, where it rides in 240 feet deep of water, it measures upwards of a third of a mile in length. Some years ago it was found that the addition of certain ingenious shackles (so to speak) controlled its movements; and by various improvements in its construction, the result has been obtained that, slave though it be, it shall weigh as little as possible on its mooring-chains. Usually, the moorings consist of a chain lying along the sea-bed for 1260 feet, with an anchor of 32 cwt., in the shape of a mushroom at either end, and a swivel in the centre, to which is attached a veering cable of 630 feet of chain. [Illustration: THE LIGHTSHIP.] Few instances are on record of a lightship having broken loose from its moorings, and none of its having suffered shipwreck. Each vessel carries, for emergencies, two bower anchors of 20 cwt. and 15 cwt.; and cables respectively 1260 and 900 feet long. Nor is it known that the crew have, on any occasion, or whatever the fury of the tempest, voluntarily changed their position. If, however, the ship should be driven from its place by the irresistible force of the elements, so that its light may become a source of danger to the mariner, they hoist a red signal and fire a gun, and generally it is soon restored to its normal situation. The peril of drifting, and the presence of mind which the necessary manœuvres require in such an event, are evidences, nevertheless, of the courage and resolution of the men who live, day and night, exposed to the caprice of the seas. As it is necessary to prepare for every accident, a spare vessel is always held in readiness at the headquarters of each district; owing to the telegraphic network which now surrounds our shores, the slightest mishap is soon made known to the authorities; and often before sunset the reserve ship, towed by a powerful steam-tug, occupies the place of the vessel which the storm has driven from its moorings. The lightships of the Trinity House are painted _red_; those of Ireland, _black_. Experiment has shown that red and black are the two colours which most vividly contrast with the prevailing hue of the sea. The name of the vessel is inscribed in large letters on its sides. A flag, bearing a cross quartered with four ships, waves at the stern.