The French Lighthouses Commission is not so splendidly lodged as the Trinity Board, nor is its Museum equal to the one at Edinburgh.[15] But, side by side with models of modern lighthouses, are models of the most ancient, from the ungainly tower whose summit was lit up with a rude fire of sea-coal, to the elegant edifice of the Héaux de Bréhat. It also contains numerous examples of all the catoptric or dioptric apparatus which are, or have been, in use, as well as specimens of clocks, buoys, and beacons. The Lighthouse Museum is, finally, the central depôt where experiments are conducted in reference to all the elements of maritime lightage, under the supreme direction of M. Emile Allard, the engineer-in-chief.
CHAPTER II.
GEOGRAPHICAL DISTRIBUTION OF LIGHTHOUSES.
In reference to the military protection of our coasts, the civilian is frequently warned of the necessity of maintaining more than one “line of defence;” a similar necessity exists as regards their complete and satisfactory lightage. We know, too, that at one point a battery is erected; at another, a simple earthwork is pronounced sufficient; at a third, the eye ranges over an intricate combination of forts. The same variety exists in the disposition of those coast-defences which are designed in the interests of secure and peaceful navigation. Follow, with the mind’s eye, the long coast-line of our country, and how many differences we shall note in the situation of its lighthouses, in their mode of construction, their elevation, their system of illumination. Each pharos has, as it were, a speech of its own; each addresses, in significant language, the seaman who turns to it for advice or warning. This points out the entrance to a commodious haven, where, after being much tossed by unquiet waves, the weary mariner may repose in safety; that indicates the site of a perilous rock or sand-bank, on which a storm-driven vessel must assuredly perish. Here we see a noble tower, whose genial rays are visible at a distance of twenty-seven nautical miles; there burns a steady light, whose extent of illumination is restricted to five miles. One is a fixed light, glowing constantly like a brilliant star; another, more mysterious, suddenly flashes forth from the deep darkness, flings over the sea its arrow of flame, and then is again extinguished, to reappear, a few moments later, in the same strange and impressive manner. Nor are all lights of an uniform colour. Some are red, with an intense ruby-like splendour; others white; others, again, are blue or green. This variety in the range and aspect of the “beacon-fires” has, like the variety in the size and position of our forts and batteries, a special object.
The system of lightage generally adopted, says M. Renard, consists in surrounding the coast with three lines of defence; the outmost being composed of lighthouses with a very extensive range. It has justly been deemed of the highest importance to signal to the mariner the proximity of the land, since it is in the waters near the coast that navigation is exposed to the greatest dangers. The littoral presents a number of capes, promontories, and headlands, more or less projecting beyond the general level, as well as islets, and reefs, and shallows, which require to be carefully avoided. Now, lighthouses of the first class, as we may call them, or “sea-lights,” are usually planted on these promontories or rocks; and along the British shore they are so arranged that it is impossible, except in a dense fog, to arrive in its neighbourhood without catching sight of one or more of them.