158 GULLIVER'S TRAVELS
into a large dome, which is therefore called Flandona Gagnole, or the Astronomer's Cave, situated at the depth of a hundred yards beneath the upper surface of the adamant. In this cave are twenty lamps continually burning, which, from the reflection of the adamant, cast a strong light into every part. The place is stored with great variety of sextants, quadrants, telescopes, astrolabes, and other astronomical instruments. But the greatest curiosity, upon which the fate of the island depends, is a loadstone of a prodigious size, in shape resembling a weaver's shuttle. It is in length six yards, and, in the thickest part, at least three yards over. This magnet is sustained by a very strong axle of adamant passing through its middle, upon which it plays, and is poised so exactly that the weakest hand can turn it. It is hooped round with a hollow cylinder of adamant, four feet deep, as many thick, and twelve yards in diameter, placed horizontally, and supported by eight adamantine feet, each six yards high. In the middle of the concave side there is a groove twelve inches deep, in which the extremities of the axle are lodged, and turned round as there is occasion.
The stone cannot be moved from its place by any force, because the hoop and its feet are one continued piece with that body of adamant which constitutes the bottom of the island.
By means of this loadstone the island is made to rise and fall, and move from one place to another. For, with respect to that part of the earth over which the monarch presides, the stone is endued at one of its sides with an attractive power, and at the other with a repulsive. Upon placing the magnet erect, with its attracting end towards the earth, the island descends; but, when the repelling extremity points downwards, the island mounts directly upwards. When the position of the stone is oblique, the motion of the island is so too. For in this magnet the forces always act in lines parallel to its direction.