« ForrigeFortsæt »
PRAISE OF PHILOSOPHY.
The Praise of Philosophy.
But now let other themes our care engage,
And from within the cherish'd heart to brace,
By Indolence and moping Fancy bred,
And Hope and Courage brighten in their stead,
Then waken from long lethargy to life
The seeds of happiness and powers of thought; Then jarring appetites forego their strife,
A strife by ignorance to madness wrought.
With fell revenge, lust that defies control,
Can mortal sight, so oft bedimm'd with tears
From Nature's face; confusion disappears,
In the deep windings of the grove, no more
The hag obscene and grisly phantom dwell; Nor in the fall of mountain-stream, or roar
Of winds, is heard the angry spirit's yell; No wizard mutters the tremendous spell, Nor sinks convulsive in prophetic swoon;
Nor bids the noise of drums and trumpets swell, To ease of fancied pangs the labouring moon,
Or chase the shade that blots the blazing orb of noon
Many a long-lingering year, in lonely isle,
Stunn'd with th' eternal turbulence of waves, Lo, with dim eyes, that never learn'd to smile,
And trembling hands, the famish'd native craves Of Heaven his wretched fare: shivering in caves,
Or scorch'd on rocks, he pines from day to day:
The surge and tempest, lighted by her ray,
PRAISE OF PHILOSOPHY.
And even where nature loads the teeming plains
Even Fancy trembles in her sprightliest mood;
Nestles each murderous and each monstrous brood,
"Twas from Philosophy man learn'd to tame
The soil by plenty to intemperance fed.
Lo, from the echoing axe, and thundering flame,
Bring health and melody to every vale:
And from the breezy main, and mountain's head,
To fan their glowing charms, invite the flutt'ring gale.
What dire necessities on every hand
Our art, our strength, our fortitude require! Of foes intestine what a numerous band
Against this little throb of life conspire! Yet Science can elude their fatal ire
Awhile, and turn aside death's levell'd dart Sooth the sharp pang, allay the fever's fire,
And brace the nerves once more, and cheer the heart,
Nor less to regulate man's moral frame
GENERAL PROPERTIES OF BODIES.
Or Avarice, a fiend more fierce than they? Flee to the shade of Academus' grove;
Where Cares molest not, Discord melts away
In harmony, and the pure passions prove
What cannot Art and Industry perform,
When Science plans the progress of their toil! They smile at penury, disease, and storm;
And oceans from their mighty mounds recoil. When tyrants scourge, or demagogues embroil A land, or when the rabble's headlong rage Order transforms to anarchy and spoil,
Deep-versed in man, the philosophic sage Prepares with lenient hand their frenzy to assuage. "Tis he alone, whose comprehensive mind,
From situation, temper, soil, and clime
Secure shall lift its head on high, nor fear
General Properties of Bodies.
Symmetrical, proportionate, having parts well adapted to each other.
Cap'illary, a term applied to tubes of a very small bore, scarcely larger than to admit a hair, derived from capillus, the Latin word for hair.
WHEN We speak of bodies, we mean substances, of whatever nature, whether solid or fluid; and matter is the general term used to denote the substance of which the different bodies are composed. As we do not suppose any body
to exist without certain properties, such as impenetrability, extension, figure, divisibility, inertness, and attraction, these, therefore, are called the general properties of bodies.
By impenetrability, is meant the property which bodies have of occupying a certain space, so that, where one body is, another cannot be, without displacing the former; for two bodies cannot exist in the same place at the same time. A liquid may be more easily removed than a solid body; yet it is not the less substantial, since it is as impossible for a liquid and a solid to occupy the same space at the same time, as for two solid bodies to do so. If some water be put into a tube closed at one end, and a piece of wood be inserted that accurately fits the inside of the tube, it will be impos sible to force the wood to the bottom, unless the water is first taken away. The air is a fluid differing in its nature from liquids, but not less impenetrable. If you endeavour to fill a phial by immersing it in water, the air will rush out in bubbles in order to make way for the water; and if you reverse the phial, and plunge it perpendicularly into the water, so that the air will not be able to escape, the water will not fill it, though it will rise a little, because it compresses the air into a smaller space in the upper part of the glass.
A body which occupies a certain space must necessarily have extension; that is to say, length, breadth, and depth. These are called the dimensions of extension, and we cannot form an idea of any body without them. The limits of extension are called figure or shape. A body having length, breadth, and depth, cannot be without form, either symme trical or irregular; and this property admits of almost an infinite variety. The natural form of mineral substances is that of crystals; many of them are very beautiful, and not less remarkable for their transparency and colour, than for their perfect regularity, as may be seen in the various museums and collections of natural history. The vegetable and animal creation appears less symmetrical, but is still more diversified in figure than the mineral kingdom. Manufactured substances assume the various arbitrary forms which the art of man designs for them.
Divisibility is that property of matter, by which its parts may be divided and separated from each other; and of this division there can be no end. We can never conceive of particle of matter so small as not to have an upper and under
GENERAL PROPERTIES OF BODIES.
GENERAL PROPERTIES OF BODIES.
surface, which might be separated, if we had instruments fine enough for the purpose. A grain of gold may be hammered by the gold-beaters to such a degree of fineness, that the two millionth part of it may be seen by the naked eye; and by the help of a microscope the fifty millionth part will be visible. There are animals, it is said, so small that a single grain of sand is larger than four millions of them. But the natural divisions of matter are still more wonderful. The fragrance of a body is a part of the body itself, and is produced by very minute particles or exhalations which escape from it. How inconceivably small must be the odoriferous particles of a carnation, which diffuse themselves through a whole garden, so that, in every part of it, its fragrance is perceptible!
The word inertness expresses the resistance which inactive matter makes to a change of state. It requires some external force to put a body which is at rest in motion; and an exertion of strength is also requisite to stop a body which is already in motion. If a ball were fired from a cannon with a certain velocity, and there were no resistance from the air, it would circulate round the earth perpetually, and never come to a state of rest. In this manner the moon goes round the earth.
By attraction is meant the tendency that bodies have to approach each other, whatever be the cause of such tendency. All bodies are composed of infinitely small particles of matter, each of which possesses the power of attracting or drawing towards itself any other particle, and of uniting with it, when sufficiently near to be within the influence of its attraction; but in minute particles this power extends to so very small a distance around them that its effect is not sensible, unless they are, or at least appear to be, in contact. It then makes them adhere together, and is hence called the attraction of cohesion. It is by this principle that bodies preserve their forms, and are prevented from falling to pieces. The cohesive attraction of solids is much greater than that of fluids; and in elastic fluids, such as air, there is no cohesive attraction among the particles, and the utmost efforts of human art have proved ineffectual in the attempt to compress them, so as to bring them within the sphere of each other's attraction, and make them cohere. If two polished plates of marble, or of brass be but together with a