When the gathering brightness of the dawn enables the form of the tower to be identified from a distance of several miles, the light is extinguished. Heavy curtains are drawn across the windows, not only to protect the lenses from the sun, but also to give a characteristic colour to the lantern. Thus, by daylight a lantern may appear to be a dull red or an intense black. To give a brilliant light by night and be a prominent landmark by day forms the dual duty of the guardian of the coast. When the lantern has cooled, the keepers coming on the day shift have to clean the lamps and put them in order for service the following evening. Everything has to be overhauled and got ready for use at a moment’s notice. The oil reservoirs have to be examined and charged, and the panes of glass, with which the lantern is glazed, cleaned and brightened. The reflectors have to be polished, for they must be kept in a constant state of mirror-like brilliancy. All brasswork has to be cleaned and polished until it gleams like burnished gold, while the rooms must be washed and kept in the pink of condition, free from the smallest specks of dust. The necessity for extreme cleanliness and spotlessness is emphasized in every lighthouse. The inspector has a highly-trained, quick eye for detecting carelessness, and he has one instinct developed peculiarly--the discovery of dust. He draws his fingers over everything, and squints quizzically at an object from all angles. Woe betide the keeper if the slightest trace of dirt is detected. Then the inspector closes the other eye, and the keeper receives a squint which does not augur well for his future. A few sharp, pointed remarks are rasped out, and it is not long before the relief-boat comes out with another man. The engineers and other representatives of authority are remorseless. A man is judged from apparently trifling details. If he permits a door-knob to become sullied, he is just as likely to overlook the polishing of the lenses, or to perform some other vital task in a perfunctory manner.