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eyelid ; and if you will watch closely, you may see it descend and return with electric velocity. It clears away the dust, and protects the eye from injury. If the eye should catch cold, the haw hardens and projects, and ignorant persons cut it off, and thus destroy this safeguard.
8. You all know, if you take a pound of iron, and make of it a rod a foot long, what weight it will support. But if it be a hollow rod, it will support a weight many times greater than before. Nature seems to have taken advantage of this also, long before mathematicians had discovered it, and all the bones of animals are hollow. The bones of birds are large, because they must be strong to move their large wings with sufficient velocity ; but they must also be light, in order to float easily upon the air.
9. Birds also illustrate another fact in natural philosophy. If you take a bag, make it air-tight, and put it under water, it will support a large weight, say an hundred pounds. But twist it, or diminish the air in it, and it will support no such weight. Now, a bird has such an air-bag; when he wishes to descend, he compresses it at will, and falls rapidly; when he would rise, he increases it, and floats with ease. He also has the power of forcing air into the hollow parts of the body, and thus to assist his flight.
10. The same thing may be observed in fishes. They also have an air-bag, to enable them to rise or sink in the water, till they find their temperature. If they wish to rise they increase it; if they wish to sink they compress it, and down they go.
11. Sometimes the fish, in sinking, makes too strong an effort to compress it; then down he goes to the bottom, and there remains for the rest of his life. Flounders and some other fish have no air-bag; and so they are never found floating on the surface, but must always be caught at the bottom.
12. In this way are the principles of science applied to almost everything.
You wish to know how to pack the greatest amount of bulk in the smallest space. The forms of cylinders leave large spaces between them. Mathematicians labored hard for a long time to find what figure could be used so as to lose no space; and at last found that it was the six-sided figure, and also that a three-plane, ending in a point, formed the strongest roof or door. The honey-bee discovered the same things a good while ago. Honey-comb is made up of six-sided figures, and the roof is built with three plane surfaces coming to a point.
13. If a flexible vessel be emptied of air, its sides will be almost crushed together by the pressure of the surrounding atmosphere. And if a tube, partly filled with fluid, be emptied of air, the fluid will rise to the top. The bee understands this, and when he comes to the cup of the tall honeysuckle, and finds that he cannot reach the sweet matter at its bottom, he thrusts in his body, shuts up the flower, and then exhausts the air, and so possesses himself of the dust and honey of the flower.
14. The feet of flies and lizards are constructed on a similar principle, and they thus walk with ease on glass or ceiling. Their feet are so made as to create a vacuum beneath them, and so they have the pressure of the atmosphere, fifteen pounds to the square inch, to enable them to hold on.
The cat has the same power to a less extent. 15. Plants require the sunlight, and some flowers turn themselves towards the sun, as it travels round from east to west. The sunflower does this, and so does a field of clover. The facts, though we have not yet got at the reason of them, are still extremely interesting.
16. The Virginia creeper throws out tendrils in the form of a foot with five toes; each toe has a large number of hairs or spines, which entering the small opening of brick or lime, swell and hold on; but when decaying, they shrink, and the plant falls off. The vanilla plant of the West Indies exhibits a similar construction, except that it winds itself around other objects.
17. The gastric juice is worthy of remark. It is a tasteless, colorless, inodorous, limpid fluid, like water, and is adapted, in different animals, to different purposes. In the hyena and other carnivorous animals, it will dissolve dead flesh. These creatures then live upon other animals, and even bones are soluble in their gastric juice, while it will not dissolve vegetables at all. On the other hand, some animals live entirely on vegetables, and their gastric juice will not dissolve animal food.
18. Man cannot alter the nature of an animal by changing its food; it will still belong to the family. In this particular bees are better instructed. When they lose their queen bee, - which is an entirely different animal from the working bee,- if you present another to them within twenty-four hours, they will not accept of her, nor obey her. They prefer taking an ordinary grub, before it has become a flyer, and feeding it with a particular food, and treating it in a particular way; and when it leaves the grub state, it becomes a queen bee, and they always suffer themselves to be governed by her.
19. The habits of ants are extremely curious. We all have heard of ant-houses, sometimes twenty feet in diameter, filled with halls and rooms of great size and strength. These and beaver-dams are constructed upon strictly mechanical principles.
20. In some insect species, the males have wings while the females have none. This is the case with the glow-worm ; and the female has the property of emitting a phosphorescent light; and were it not for this, the glow-worm would never find its mate.
ROUSE TO SOME NOBLE WORK.
1. WOULDst thou from sorrow find a sweet relief?
Or is thy heart oppressed with woes untold?
Leaf after leaf, its bosom rich and fair,
2. Wake, thou that sleepest in enchanted bowers,
Lest these lost years should haunt thee on the night
An angel's wing would droop if long at rest,
3. Some high or humble enterprise of good
Contemplate, till it shall possess thy mind,
Strength to complete, and with delight review,
4. No good of worth sublime will Heaven permit
To light on man as from the passing air;
And learning is a plant that spreads and towers
That, 'mid gay thousands, with the suns and showers Of half a century, grows alone before it flowers.
5. Has immortality of name been given
To them that idly worship hills and groves,
Or did Paul gain heaven's glory and its peace,
6. Beware lest thou, from sloth, that would appear
But lowliness of mind, with joy proclaim
'Tis infamy to die and not be missed,
7. Rouse to some work of high and holy love,
And thou an angel's happiness shalt know,-
Shall deck thy grave with amaranthine flowers,