As may be imagined, upon a sea-rock, owing to the slender proportions of the tower, the quarters are inevitably very cramped, with no facilities for the men to stretch their limbs. The manner in which space is economized in the small circular apartments is astonishing. The essential furniture is built to the wall, and liberal cupboard space is provided, the governing consideration being to provide the men with as much open space as the restricted circumstances will permit. The only exercise that the men can obtain in the open air is upon the narrow shelf forming the landing platform, or the narrow gallery around the lantern. In the majority of circumstances it is less than that provided for the benefit of a prisoner in an exercise yard. The lamp is lighted at dusk, and, unless it is a fixed white light, the clockwork driving the occulting and revolving mechanism has to be wound up. Seeing that this entails the lifting of a ton or so up the vertical cylinder in which the weight travels, this is no mean task in itself. Unremitting vigilance has to be maintained while the lamp is burning. It demands attention from time to time, while, should anything serious go wrong, the attendant must bring the reserve lamp into service without a moment’s loss of time and without interruption of the ray. “The light must not go out!” That is the inflexible rule of all attended lights between the two Poles. Even if it failed only for a minute, the circumstance would not escape observation. Some vessel would detect the breakdown; it would be recorded in the captain’s log-book. When he touched the first port, intimation would be sent to the organization responsible for the beacon, setting forth the fact that on such and such a night, at a certain hour, this light was not showing in accordance with the official light list, or was giving a warning different from that laid down for the guidance of the seafarer. An inquiry would be instituted immediately to ascertain the reason, and the light-keeper probably would find himself in an awkward position, although months might have elapsed since the incident. There is nothing haphazard about the control of lights. The circumstances are too serious to permit the slightest deviation from hard-and-fast regulations. The passing mariner is entirely dependent upon these blazing guardians, maybe from a distance of fifteen miles or more. He has his chart wherewith he is able to steer his way, but he must have certain marks to guide him at night, so that he may be sure of his course and position. Accordingly, every lighthouse possesses some individual characteristic in regard to its light. As explained elsewhere, it may be a group flash, an occulting flash of a distinctive nature, a revolving light which completes a revolution once in a certain period of time, or a fixed blaze.