CHAPTER XI.
THE CASKETS.
IT was the Caskets Light.
A lighthouse of the nineteenth century is a high cylinder of masonry, surmounted by scientifically constructed machinery for throwing light. The Casket lighthouse in particular is a white tower supporting three light-rooms. These three chambers revolve on clock-wheels, with such precision that the man on watch who sees them from sea can invariably take ten steps during their irradiation, and twenty-five during their eclipse. Everything is based on the focal plan and on the rotation of the octagon drum, which is formed of eight wide simple lenses in range, having above and below it two series of dioptric rings; it is protected from the violence of the winds and waves by glass a millimetre thick, yet sometimes broken by the sea-eagles, which dash themselves like great moths against these gigantic lanterns. The building which encloses and sustains this mechanism, and in which it is set, is also mathematically constructed. Everything about it is plain, exact, bare, precise, correct. A lighthouse is a mathematical figure.
In the seventeenth century a lighthouse was a sort of ornament to the sea-shore. The architecture of a lighthouse tower was magnificent and extravagant. It was covered with balconies, balusters, lodges, alcoves,
