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the celebrated Dr. Black, that if a thin bag were filled with this gaseous substance, it would, according to the established laws of specific gravity, rise in the common atmosphere; but he did not pursue the inquiry. The same idea was conceived by Mr. Cavallo, to whom is generally ascribed the honour of commencing the experiments on this subject. He had made but little progress, however, in these experiments, when the discovery of Stephen and John Montgolfier, papermanufacturers of France, was announced in 1782, and engaged the attention of the philosophical world. Observing the natural ascent of smoke and clouds in the atmosphere, those artists were led to suppose that heated air, if enclosed in a suitable covering, would also prove buoyant. After several smaller experiments, by which this idea was fully confirmed, they inflated a large balloon with rarefied air, which immediately and rapidly rose to the height of six thousand feet, and answered their most sanguine expectations.

It was soon found that machines of this kind might be so contrived, as to convey small animals, and even human beings, through the air with ease. The first adventurer in this aerial navigation was Pilatre de Rozier, a daring Frenchman, who rose in a large balloon from a garden in the city of Paris, on the 15th of October, 1783, and remained a considerable time suspended in the air. He made several aerial voyages afterwards of greater extent, and in two of them was attended by other persons. In a short time, however, the use of rarefied air in aërostation was for the most part laid aside, as inconvenient and unsafe. On recurring once more to the discovery of Mr. Cavendish, the philosophers of Paris concluded that a balloon, inflated with hydrogen gas, would answer all the purposes of that contrived by the Montgolfiers, and would also possess several additional advantages. They made their first experiment in August, 1783, which was attended with complete success. Since that time, air-balloons filled with rarefied air have not been generally used.

The first aerial voyage in England was performed by Vincent Lunardi, a native of Italy. The diameter of his balloon was thirty-three feet. Soon after, Mr. Blanchard ascended, carrying up a pigeon, which flew away from the boat, laboured for some time with its wings to sustain itself in the air, and finally returned and rested on one side of the boat. He ascended so high as to experience great difficulty

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of breathing, but perceiving the sea before him, he descended near Ramsey, about seventy-five miles from London, having travelled at the rate of nearly twenty miles an hour.

The singular experiment of ascending into the atmosphere with a balloon, and of descending with a machine, called a parachute, in the form of a large umbrella, was performed by Mr. Garnerin in 1802. The weather was clear and pleasant, and the wind was gentle. In about eight minutes the balloon and parachute had ascended to an immense height, and Mr. Garnerin in the basket, could scarcely be perceived. While the spectators were contemplating the grand sight before them, Mr. Garnerin cut the rope, and in an instant he was separated from the balloon, trusting his safety to the parachute. Before the parachute opened, he fell with great velocity; but as soon as the parachute was expanded, which took place a few moments after, the descent became very gentle and gradual. It was observed that the parachute, with the appendage of cords and basket soon began to vibrate like the pendulum of a clock, and the vibrations were so great, that more than once the parachute, and the basket with Mr. Garnerin, seemed to be on the same level, or quite horizontal; the extent of the vibrations, however, diminished as he descended. On coming to the earth, he experienced some strong shocks, but soon recovered, and remained without any material injury.

The fate of Rozier, the first aerial navigator, and of his companion Romain, has been much lamented. They ascended with an intention of crossing the channel to England. Their machine consisted of a spherical balloon, filled with hydrogen gas, and under this balloon, a smaller one filled with rarefied air, designed to diminish the specific gravity of the whole apparatus. For the first twenty minutes they seemed to pursue the proper course; but the balloon appeared to be much inflated, and the aëronauts appeared anxious to descend. Soon, however, when they were at the height of three quarters of a mile, the whole apparatus was in flames, and the unfortunate adventurers fell to the ground, and were killed.

The invention of balloons cannot be considered as having added much to the comfort or utility of man. The only practical purposes which it has been made to subserve, are those of aiding meteorological inquiries, and of inspecting

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the fortifications and reconnoitring the camp of an enemy, which could not be approached by other means. The difficulties, under which this species of navigation labours, appear at present to be insurmountable; and the want of some means to control and regulate the movements of the aerial vessel is so essential, as to excite a fear that it cannot be supplied.

QUESTIONS.-1. What is aĕrostation? 2. What is the best form for a balloon? 3. What are the two kinds of balloons? 4. How is a balloon filled with hydrogen gas? 5. Who invented the first aërostatic machine, and what was the result? 6. What discovery did Cavendish make? (Hydrogen gas is 14 times lighter than common air, -see Lesson on water.) 7. What afterwards occurred to Dr. Black? 8. What idea did Cavallo conceive?-what is ascribed to him? 9. What discovery did the Montgolfiers make? 10. Who was the first aerial navigator? 11. What was the next discovery in this science? 12. What is said of, the ascent of Mr. Blanchard? 13. Describe the experiment of Mr. Garnerin. 14. What was the fate of Rozier and Romain? 15. What is said of the advantages which have been derived from balloons? 16. Of the difficulties under which this species of navigation labours? [NOTE. Small balloons may be made of thin strips of bladder, or other membrane, glued together.]

LESSON 75.

Natural History.

Pellu'cid, clear, transparent, not opaque.

THOSE Who with a philosophical eye have contemplated the productions of Nature, have all, by common consent, divided them into three great classes, called the Animal, the Vegetable, and the Mineral or Fossil kingdoms. These terms are still in general use, and the most superficial observer must be struck with their propriety. Animals have an organized structure which regularly unfolds itself, and is nourished and supported by air and food; they consequently possess life, and are subject to death; they are moreover endowed with sensation, and with spontaneous, as well as voluntary, motion. Vegetables are organized, supported by air and food, endowed with life, and subject to death as well as animals. They have in some instances spontaneous, though we know not that they have voluntary motion. They are sensible to the action of nourishment, air, and light, and

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either thrive or languish according to the wholesome or hurtful application of these stimulants. The spontaneous movements of plants are almost as readily to be observed as their living principle. The general direction of their branches, and especially of the upper surface of their leaves, though repeatedly disturbed, to the light, the unfolding and closing of their flowers at stated times, or according to favourable or unfavourable circumstances, with some still more curious particulars, are actions undoubtedly depending on their vital principle, and are performed with the greater facility in proportion as that principle is in its greatest vigour. Plants alone have a power of deriving nourishment, though not indeed exclusively, from inorganic matter, mere earths, salts, or airs, substances certainly incapable of serving as food for any animals, the latter only feeding on what is or has been organized matter, either of a vegetable or animal nature. So that it would seem to be the office of vegetable life alone to transform dead matter into organized living bodies.

The Mineral kingdom can never be confounded with the other two. Fossils are masses of mere dead unorganized matter, subject to the laws of chemistry alone; growing indeed, or increasing by the mechanical addition of extraneous substances, or by the laws of chemical attraction, but not fed by nourishment taken into an organized structure. Their curious crystallization bears some resemblance to organization, but performs none of its offices, nor is any thing like a vital principle to be found in this department of nature. If it be asked what is this vital principle, so essential to animals and vegetables, but of which fossils are destitute, we must own our complete ignorance. We know it, as we know its omnipotent Author, by its effects. The infinitely small vessels of an almost invisible insect, the fine and pellucid tubes of a plant, all hold their destined fluids, conveying or changing them according to fixed laws, but never permitting them to run into confusion, so long as the vital principle animates their various forms. But no sooner does death happen, than, without any alteration of structure, any apparent change in their material configuration, all is reversed. The eye loses its form and brightness; its membranes let go their contents, which mix in confusion, and thenceforth yield to the laws of chemistry alone. Just so it happens, sooner or later, to the other parts of the animal as

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well as vegetable frame. Chemical changes immediately follow the total privation of life, the importance of which becomes instantly evident when it is no more. If the human understanding can in any case flatter itself with obtaining, in the natural world, a glimpse of the immediate agency of the Deity, it is in the contemplation of this vital principle, which seems independent of material organization, and an impulse of his own divine energy.

The man who surveys the vast field of nature, and devotes a portion of his time to the study of the principles which influence, or govern, the motions of animated beings, however minute they may be, will not only derive pleasure from the pursuit, but he will gain the only means of discovering the object and utility of their creation. And as he journeys along from one gradation of knowledge to another, he will become more and more intimate with the designs of the great Creator of all. He will gain a more comprehensive view of that wonderful and illimitable power which hath organized the universe, for purposes with which, in the fulness of time, the wise and the virtuous will doubtless be made acquainted. But knowledge must ever be progressive; and he who makes the attempt to read the characters by which the wisdom, power, beneficence, and eternal nature of God is stamped upon every thing here below, will not do it in vain.

He suits to nature's reign th' inquiring eye,
Skill'd all her soft gradations to descry;

From Matter's mode through Instinct's narrow sway,

To Reason's gradual but unbounded way,

And sees through all the wonder-varied chain

No link omitted, no appendage vain,

But all supporting and supported, till

The whole is perfect as the AUTHOR'S will.

Hence even the meanest points of Nature's care
Fix his attention—his attachment share:

The pebble, through pellucid waters shown,

The moss that clothes-the shrub that cleaves to stone,
The modest-tinted flowers that deck the glade,
The aged tree that spreads its awful shade,
The feathered race that wing the ethereal way,
The insect tribes that float upon the ray,

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