CHAPTER III.
A phenomenon solved by modern philosophy and astronomy. The Laputians'great improvements in the latter. The king's method of suppressinginsurrections.
I desired leave of this prince to see the curiosities of the island,which he was graciously pleased to grant, and ordered my tutor to attendme. I chiefly wanted to know, to what cause, in art or in nature, itowed its several motions, whereof I will now give a philosophical accountto the reader.
The flying or floating island is exactly circular, its diameter 7837yards, or about four miles and a half, and consequently contains tenthousand acres. It is three hundred yards thick. The bottom, or undersurface, which appears to those who view it below, is one even regularplate of adamant, shooting up to the height of about two hundred yards.Above it lie the several minerals in their usual order, and over all is acoat of rich mould, ten or twelve feet deep. The declivity of the uppersurface, from the circumference to the centre, is the natural cause whyall the dews and rains, which fall upon the island, are conveyed in smallrivulets toward the middle, where they are emptied into four largebasins, each of about half a mile in circuit, and two hundred yardsdistant from the centre. From these basins the water is continuallyexhaled by the sun in the daytime, which effectually prevents theiroverflowing. Besides, as it is in the power of the monarch to raise theisland above the region of clouds and vapours, he can prevent the fallingof dews and rain whenever he pleases. For the highest clouds cannot riseabove two miles, as naturalists agree, at least they were never known todo so in that country.
At the centre of the island there is a chasm about fifty yards indiameter, whence the astronomers descend into a large dome, which istherefore called _flandona gagnole_, or the astronomer's cave, situatedat the depth of a hundred yards beneath the upper surface of the adamant.In this cave are twenty lamps continually burning, which, from thereflection of the adamant, cast a strong light into every part. Theplace is stored with great variety of sextants, quadrants, telescopes,astrolabes, and other astronomical instruments. But the greatestcuriosity, upon which the fate of the island depends, is a loadstone of aprodigious size, in shape resembling a weaver's shuttle. It is in lengthsix yards, and in the thickest part at least three yards over. Thismagnet is sustained by a very strong axle of adamant passing through itsmiddle, upon which it plays, and is poised so exactly that the weakesthand can turn it. It is hooped round with a hollow cylinder of adamant,four feet yards in diameter, placed horizontally, and supported by eightadamantine feet, each six yards high. In the middle of the concave side,there is a groove twelve inches deep, in which the extremities of theaxle are lodged, and turned round as there is occasion.
The stone cannot be removed from its place by any force, because the hoopand its feet are one continued piece with that body of adamant whichconstitutes the bottom of the island.
By means of this loadstone, the island is made to rise and fall, and movefrom one place to another. For, with respect to that part of the earthover which the monarch presides, the stone is endued at one of its sideswith an attractive power, and at the other with a repulsive. Uponplacing the magnet erect, with its attracting end towards the earth, theisland descends; but when the repelling extremity points downwards, theisland mounts directly upwards. When the position of the stone isoblique, the motion of the island is so too: for in this magnet, theforces always act in lines parallel to its direction.
By this oblique motion, the island is conveyed to different parts of themonarch's dominions. To explain the manner of its progress, let _A_ _B_represent a line drawn across the dominions of Balnibarbi, let the line_c_ _d_ represent the loadstone, of which let _d_ be the repelling end,and _c_ the attracting end, the island being over _C_: let the stone beplaced in position _c_ _d_, with its repelling end downwards; then theisland will be driven upwards obliquely towards _D_. When it is arrivedat _D_, let the stone be turned upon its axle, till its attracting endpoints towards _E_, and then the island will be carried obliquely towards_E_; where, if the stone be again turned upon its axle till it stands inthe position _E_ _F_, with its repelling point downwards, the island willrise obliquely towards _F_, where, by directing the attracting endtowards _G_, the island may be carried to _G_, and from _G_ to _H_, byturning the stone, so as to make its repelling extremity to pointdirectly downward. And thus, by changing the situation of the stone, asoften as there is occasion, the island is made to rise and fall by turnsin an oblique direction, and by those alternate risings and fallings (theobliquity being not considerable) is conveyed from one part of thedominions to the other.
But it must be observed, that this island cannot move beyond the extentof the dominions below, nor can it rise above the height of four miles.For which the astronomers (who have written large systems concerning thestone) assign the following reason: that the magnetic virtue does notextend beyond the distance of four miles, and that the mineral, whichacts upon the stone in the bowels of the earth, and in the sea about sixleagues distant from the shore, is not diffused through the whole globe,but terminated with the limits of the king's dominions; and it was easy,from the great advantage of such a superior situation, for a prince tobring under his obedience whatever country lay within the attraction ofthat magnet.
When the stone is put parallel to the plane of the horizon, the islandstands still; for in that case the extremities of it, being at equaldistance from the earth, act with equal force, the one in drawingdownwards, the other in pushing upwards, and consequently no motion canensue.
This loadstone is under the care of certain astronomers, who, from timeto time, give it such positions as the monarch directs. They spend thegreatest part of their lives in observing the celestial bodies, whichthey do by the assistance of glasses, far excelling ours in goodness.For, although their largest telescopes do not exceed three feet, theymagnify much more than those of a hundred with us, and show the starswith greater clearness. This advantage has enabled them to extend theirdiscoveries much further than our astronomers in Europe; for they havemade a catalogue of ten thousand fixed stars, whereas the largest of oursdo not contain above one third part of that number. They have likewisediscovered two lesser stars, or satellites, which revolve about Mars;whereof the innermost is distant from the centre of the primary planetexactly three of his diameters, and the outermost, five; the formerrevolves in the space of ten hours, and the latter in twenty-one and ahalf; so that the squares of their periodical times are very near in thesame proportion with the cubes of their distance from the centre of Mars;which evidently shows them to be governed by the same law of gravitationthat influences the other heavenly bodies.
They have observed ninety-three different comets, and settled theirperiods with great exactness. If this be true (and they affirm it withgreat confidence) it is much to be wished, that their observations weremade public, whereby the theory of comets, which at present is very lameand defective, might be brought to the same perfection with other arts ofastronomy.
The king would be the most absolute prince in the universe, if he couldbut prevail on a ministry to join with him; but these having theirestates below on the continent, and considering that the office of afavourite has a very uncertain tenure, would never consent to theenslaving of their country.
If any town should engage in rebellion or mutiny, fall into violentfactions, or refuse to pay the usual tribute, the king has two methods ofreducing them to obedience. The first and the mildest course is, bykeeping the island hovering over such a town, and the lands about it,whereby he can deprive them of the benefit of the sun and the rain, andconsequently afflict the inhabitants with dearth and diseases: and if thecrime deserve it, they are at the same time pelted from above with greatstones, against which they have no defence but by creeping into cellarsor caves, while the roofs of their houses are beaten to pieces. But ifthey still continue obstinate, or offer to raise insurrections, heproceeds to the last remedy, by letting the island drop directly upontheir heads, which makes a universal destruction both of houses and men.However, this is an extremity to which the prince is seldom driven,neither indeed is he willing to put it in execution; nor dare hisministers advise him to an action, which, as it would render them odiousto the people, so it would be a great damage to their own estates, whichall lie below; for the island is the king's demesne.
But there is still indeed a more weighty reason, why the kings of thiscountry have been always averse from executing so terrible an action,unless upon the utmost necessity. For, if the town intended to bedestroyed should have in it any tall rocks, as it generally falls out inthe larger cities, a situation probably chosen at first with a view toprevent such a catastrophe; or if it abound in high spires, or pillars ofstone, a sudden fall might endanger the bottom or under surface of theisland, which, although it consist, as I have said, of one entireadamant, two hundred yards thick, might happen to crack by too great ashock, or burst by approaching too near the fires from the houses below,as the backs, both of iron and stone, will often do in our chimneys. Ofall this the people are well apprised, and understand how far to carrytheir obstinacy, where their liberty or property is concerned. And theking, when he is highest provoked, and most determined to press a city torubbish, orders the island to descend with great gentleness, out of apretence of tenderness to his people, but, indeed, for fear of breakingthe adamantine bottom; in which case, it is the opinion of all theirphilosophers, that the loadstone could no longer hold it up, and thewhole mass would fall to the ground.
By a fundamental law of this realm, neither the king, nor either of histwo eldest sons, are permitted to leave the island; nor the queen, tillshe is past child-bearing.