appear quite impossible. By supposing the existence of a perfect vacuum, the pressure of the atmosphere, which keeps the hemispheres one against the other, acts like two columns of quicksilver about 2 feet 6 inches high, pressing, in opposite directions, against two circular disks placed in juxta-position, and whose diameter is equal to that of the spheres. Let us suppose a diameter of 1 foot 7 inches; the superficies of each disk will be about 6 square feet. Now, a column of quicksilver 2 feet 6 inches high exercises on every square inch a pressure of about 56 pounds. Thus, reasoning on the hypothesis of a perfect vacuum, it would be necessary to use a force of traction of full 4,800 pounds in order to separate the two hemispheres. Now, horses, when harnessed,

The cylindri

or even a greater number of able-bodied men." cal barrel of a pump, furnished with a cock, x, rests its lower part on a support, w B. In this barrel works a piston, RR, represented separately in fig. 7, and on the handle of which, QP, a number of men are exercising as much force of traction as they can by means of a pulley. The stay, oo, prevents the piston from rising high enough to slip out of the band. Everything being thus arranged, the cock of a glass spherical receiver of some size, and in which a vacuum has been formed, is fitted on to the cock x. With the two cocks thus placed one in the other, and with the piston exactly filling the bore of the pump, so that no air can enter when the two cocks are turned on, the air contained in the barrel of the pump will

are not capable, on an average, of exercising a greater force of traction than 560 pounds, and even then for only a very short time. It would thus be necessary to harness eight horses to each hemisphere in order to effect a separation. It is true that the vacuum cannot be perfect in the interior of the sphere; but then, by only augmenting the diameter by a little more than half an inch, the power of resistance is doubled, the vacuum being supposed the same in the interior.

The clever experimentalist had easily discovered the cause of the phenomenon, and had varied its effects in order to render it still more astonishing. By letting a succession of small quantities of air into the globe, by turning on the cock and turning it off again immediately, the power of resistance of the two disks was rapidly diminished, and, at last, entirely destroyed. If the receiver were hung by its upper ring to a strong hook, it required, in order to separate the two hemispheres, a weight little less than that which it had been calculated was necessary in the hypothesis of a perfect vacuum. When the separation took place, the sudden admission of the air produced an explosion similar to that of a piece of artillery. Fig. 10 represents the apparatus employed.

Figs. 11 and 12 clearly explain another experiment, to which the discoverer himself tersely gives the name of "a glass vase, which possesses the force of drawing to it 20, 30, 40, 50,

These magnificent experiments have been related by the inventor in a remarkable work, published at Amsterdam, in 1670. An account of them had already appeared, under the title of "Wonders of Madgeburg," in the "Technica Curiosa" of Father Schott, who published as well the "Wonders of England," according to the naïvely enthusiastic style of the epoch. Robert Boyle, a clever English natural philosopher, profiting by the labours of Otho Guericke, had repeated and varied his experiments, had constructed new machines, and had, in a word, gone a step beyond the German philosopher. For a long time the air-pump was designated in England by the name of Boyle's pump or Boyle's vacuum, but Robert Boyle never claimed priority in this respect. There exists a letter of his written two years after the publication of Father Schott's first work, and in this letter he explicitly states that he was preceded in his scientific labours by the distinguished Otho Guericke. He adds, however, that, in order to remedy certain inconveniences existing in the latter's air-pump, he begged Messrs. Hook and Gratorix to invent some new machines which would be more easy to work, and that, after several useless attempts, Hook succeeded in making an instrument far preferable to the one of Madgeburg.

Robert Boyle soon employed a better engine than the preceding one, but, like that, only furnished with one barrel; and, at last, in order to perform a series of new experiments with a vacuum, he employed a machine different from both of these, and which was the production of the celebrated and unfortunate Frenchman, Denis Papin. In order that no doubt may exist with respect to this subject, we will here give a passage from the celebrated geometrician and philosopher Cotes, of whom Newton himself said, that, "if Mr. Cotes had lived, we should know something." The following is the passage, extracted from the lectures given at Cambridge by Cotes on experimental physics.

This machine "was the contrivance of Mr. Papin, whose assistance Mr. Boyle did also make use of in the trials themselves. This third air-pump was much more convenient than the former, and the advantage lay chiefly in these two particulars. First, whereas the former engines had only one single barrel and one sucker or embolus, this was furnished with two barrels and two suckers, and these two suckers being alternately raised and depressed, caused the evacuation to be continual; which effect could not be obtained by a single sucker, it being necessary that the evacuation should cease during the time in which the sucker is forced in towards the bottom of the barrel. But, besides this advantage of performing the operation in half the time it could be done with a single sucker, the labour also in doing it was greatly lessened. The chief difficulty complained of in single-barrelled pumps is the very great resistance which the external air makes against the sucker as it is drawn outwards; and this resistance increases as the receiver is more and more exhausted, the counterbalance of the internal against the external air being thereby more and more diminished, so that if the barrel be of a considerable wideness, it may be impossible for the strength of any one man to work the engine any longer. Now this resistance of the external air is entirely taken off by making use of two suckers instead of one. They are so connected together by the fabric of the instrument, that as the one descends, so the other must of necessity ascend at the same time; and, consequently, the resistance of the external air, hindering the ascent of the one as much as it promotes the descent of the other, by contrary effects loses its force upon both. I cannot illustrate this better than by comparing it with a balance. If a single weight be placed at one of its extremities, we perceive a difficulty in moving the beam to make the weight ascend, and this difficulty increases as the weight is greater. But if you place another weight equal to the former at the opposite extremity, the difficulty in moving the beam will entirely cease, how great soever the two equal weights may be supposed to be.

"The other particular in which this air-pump excelled the former, was the advantage of its valves. In the two first

engines, whilst the sucker was drawn outwards, you was obliged at the same time to turn a stop-cock, to make way for the air in the receiver to pass from thence into the barrel; and when this air was to be excluded from the barrel, as the sucker was moved inwards, you was obliged again to turn the stop-cock, to prevent the air from reverting into the receiver; and at the same time to give it a passage outwards, a stopple or plug was to be removed, which closed the hole through which it was to pass, and then again this hole was to be stopped up and the cock to be turned again as more air was drawn from the receiver, and this labour to be repeated perpetually, so long as you continued to work the pump. Now the valves which, in the third air-pump, supplied the place of the plug and stop-cock, were undoubtedly much more convenient, in that of themselves they opened to give the air a passage forwards, and shut to prevent its return back again."

Fig. 13 represents an apparatus arranged according to

FIG. 13.-Double-acting pneumatic machine, according to the system of Papin.

this system, of which the following is a summary description:

A and B are two cylinders, in each of which is a piston. The rods, c, of the pistons are furnished with teeth, and they are worked by means of a wheel, R, which in its alternate movement describes about the third of a circle. On the plate, G, are placed the vessels from which it is required to expel the air, and which communicate by pipes, x x x, with the cylinders. Each of these pumps is furnished with a cock placed a little below their ends. The handles of these cocks are indicated by L L, and they are connected one with the other by the brass rod P P, so that both cocks are always moved together. To the axle-tree of the wheel, R, is joined, from behind, a sort of iron cross, N M, which turns the cocks. This ingenious piece of mechanism is rather more complicated than that of the simple valves; but its principle is the same, while it is, perhaps, the means of closing any vessel in a more hermetical

manner.

THE ARTS FOUR THOUSAND YEARS AGO.

THE Egyptians considered themselves the oldest nation in the world, except the Phrygians, to whom they were obliged to yield the palm, from an experiment made by one of their kings, which would by no means satisfy the logical spirit of the present age. But the nation which flourished on the banks of the Nile, and left behind them monuments which have been the wonder and admiration of forty generations, were themselves but colonists, not an indigenous stock in the land which they reclaimed from a state of swamp and mire, and made the most fertile in the world. It is supposed, even, that the materials of some of their most ancient and most celebrated structures were taken from the ruins of buildings still more ancient, of whose founders tradition itself has nothing to tell. It is certain, however, that they must have been emigrants from another region, and that the primitive nursery of our race was in Asia.

But where was the first human pair located? Col. Chesney, in the interesting narrative on his expedition to explore the Euphrates, of which we may give some account hereafter, expresses his belief that "the land of Eden" was central Armenia; and he has accordingly laid it down on the index map. He identifies the Halys and Araxes, whose source is within a short distance of the Euphrates and Tigris, with the Pison and Gihon of Scripture, while he considers the country within the Halys as the land of Havilah, and that which borders on the Araxes as the much-disputed territory of Cush.

There is no doubt that universal history and tradition direct us to some point in the eastern continent as the original home of man. Wherever he has been found in the other continents, all his records and traditions declare—“This is not the native place of my earliest progenitors. They were strangers and sojourners here, having migrated from the land of their fathers." Guyot, in his lectures "On the Earth and Man,” maintains that western Asia is the original country of the white race, the most perfect in body and mind. Following the footprints of the primitive nations, step by step backward, to their point of departure, we are brought by every route to the centre of this plateau. It is here, also, in Upper Armenia and Persia, that we find the finest type of the historical nations, among whom civilisation and the arts flourished earliest. "First, the Zena nation dwells along the Araxes; then, by the road of the plateau, proceeds to found in the plains of the Oxus one of the most remarkable and the most mysterious of the primitive communities of Asia. A branch of the same people, or a kindred people-the intimate connexion of their language confirms it-descends into India, and there puts forth the brilliant and flourishing civilisation of the Brahmins. Arabia and the south of Africa receive their inhabitants by Loristan; south Europe perhaps by the same route, through Asia Minor; the North, finally, through the Caucasus, whence issue, in succession, the Celts, the Germans, and many other tribes, who hold in reserve their native vigour for the future destinies of the continent."

Tradition everywhere represents the race as descending from the high table-lands of Asia, and then spreading east, west, south, and north, and settling in the low fertile plains, where history first finds them united in societies or nations, tilling the soil, building cities, cultivating the arts, and arriving rapidly at a degree of magnificent and splendid civilisation, of which the temples, palaces, sculptures, and monuments of Egypt, India, and Nineveh afford still living witnesses.

The picture of Egypt, drawn by Herodotus, is very interesting; but it is an imperfect outline compared with what is exhibited by its own exquisitely sculptured monuments, which reveal the arts and sciences in a state of astonishing perfection for that age of the world, and prove the existence of mechanical powers which modern science cannot equal. Man has been described by an ancient Greek writer as "an imitative animal." The Egyptians were peculiarly so. There is not a trade, occupation, or amusement, which distinguished their country, not a natural production, whose likeness they have not transmitted

to posterity, engraved upon the face of the everlasting rock with a distinctness of outline and a delicacy of execution which demonstrate their skill as artists. They show us the agricul turists in the field, the artificer in his shop, the cooks in the kitchen, the nobles at their banquets, the priests in the temple, the soldiers in their camp, the sportsmen with their gearhunting and fishing,-the social parties at draughts and other games, and the children at their play, amusing themselves with their dolls and toys.

In reference to their stupendous monuments, also, they give us some information; indeed these, to a certain extent, preserve on their faces their own written and pictorial history. We see the men quarrying the huge masses of rock out of which they shaped their monster idols; we see that the stones were drawn by bullocks, on a sledge, down an inclined plane to the Nile, a certain liquid being poured on to make the road smooth. But how did they get the colossal figures on the sledges, and down the river, and then up to the sites which they now occupy? If we look at the magnitude of some of these transported fragments of rock, we shall be convinced that there is a mechanical secret still buried under the pyramids of Egypt fully as marvellous as any connected with the steam-engine. For example: the obelisks conveyed from Syene to Thebes are from 70 to 90 feet in length; and the one at Karnac weighs about 297 tons. A statue at the Ramessium weighs upwards of 887 tons, and must have been brought 138 miles! Herodotus mentions a Monolith temple-one composed of a single stone-at Buto, in the Delta, which was brought from the Elphantine-and it was reckoned from its dimensions to be 5,000 tons in weight. By what mechanical power, or by what sort of machinery, was this mass conveyed from place to place?

The efflorescence of civilisation depicted on the existing Egyptian monuments 3,500 years ago, is truly wonderful. The children of the Egyptians were then taught writing, arithmetic, and geometry. They had a numerous and splendid hierarchy, learned in divinity and astronomy, conducting a gorgeous worship, in temples so vast and grand, that York Minster, St. Paul's, and St. Peter's, were but parish churches in comparison. At Heliopolis, anciently called On, celebrated as a seat of learning, where Herodotus and Plato resorted for wisdom, stood a magnificent temple of the sun. This vast structure was surrounded with many obelisks, one of which remains still standing amidst the ruins, covered from the base to the top with birds and beasts sculptured with extraordinary accuracy. Another of these obelisks now stands near the church of St. John Lateran at Rome. It is supposed to be the largest in the world, the shaft being 105 feet in height, and it is also adorned with the finest sculptures. A ship was built to bring it to Rome, rowed by 300 men,

The Egyptians were ignorant of perspective; but their architects knew well how to produce a grand and awe-inspiring effect by the accessories to their temples and palaces. Long avenues of obelisks and colossal statues led to the stupendous temple, which was enclosed by vast circles of a similar kind; within the enclosure was a large court, solemnly shaded with great old trees, and then the priests ascended many a flight of massive stairs to the sanctuary of the god.

How magnificent must have been the conceptions of the Egyptian architects! And the kings-how great their longing for immortality - how far down the vista of future ages reached their views-how tremendous the despotic power they wielded to accomplish their sublime purposes! Think of one of their pyramids, 460 feet high, more than 3,000 feet in circumference, with space for 5,000 or 6,000 corpses, and occupying 100,000 men for twenty years in the erection! What modern king undertakes such a task as this for any purposes however useful? If those old Egyptians had known the power of steam, and had the art of constructing railroads, what wonders might they not have accomplished for the mankind, instead of devoting their gigantic glorify a gloomy and stupid idolatry, and attempt to immortalise their own mummi we behold a more affecting illustration of

ness and meanness of the human mind, of sublime genius and degrading superstition, the loftiest and most cultivated intellect lavishing its divinest resources on the worship of beasts and reptiles !

From the remnants of the ancient Egyptian civilisation preserved in the monuments, we learn how far the mother-nations of the earth had advanced in the cultivation of the arts of civilised life, and how immense the distance between their social condition and the savage state. In this respect Egypt represents many contemporary nations; we learn from Scripture that Nineveh was a great city; and Herodotus tells us that it was the capital of the dominant power in Asia before the rise of Babylon. This great city," the glory of the Chaldeans," which derived its religion and its arts from Egypt, was for centuries the admiration of the world; and for its extent, the magnitude of its public buildings, the strength of its fortifications, its wealth, magnificence, and luxury, has never been surpassed. Numberless other cities sprung up throughout Asia, the most celebrated of which was Palmyra, -truly a city of palaces, as if created by enchantment in the desert, surrounded by an oasis of marvellous fertility, and attracting to its crowded streets the commerce of the East. But in the course of ages their riches, and the effeminacy generated by luxury and vice, tempted the approach of the barbarous conqueror and ruthless spoiler, who converted their grandeur and beauty into a mass of ruin.

But civilisation did not perish. Nor could the destroyer obliterate all the vestiges of glory. The artists of Egypt have their reward. Their works have lived to instruct and astonish the 19th century of the Christian era. The papyrus, indeed, betrayed its trust, and the embalmed mummy has little to reveal; but the stones, more durable than brass or iron, have faithfully kept the records committed to them by that wonderfully hopeful generation which built the Pyramids, and temples, and tombs, which render the valley of the Nile such a land of mystery. Never were stones so full of sermons, and the perusal of them may well abate the self-sufficiency and self-glorification of modern society.

They tell us of a well-ordered society, under an august monarchy and learned priesthood, with life and property protected by laws justly administered, and enforced by a standing army; of trade and commerce flourishing; of business systematically pursued, with its well-regulated markets, and its deeds and contracts carefully prepared; of well-built towns, paved streets, country houses and villas, with their gardens and pleasure grounds; of a nobility and gentry living in splendour, and enjoying every luxury of the toilette and the table, using cosmetics which have preserved their rich perfume in bottles to our own time, and viands which might satisfy a modern alderman, — going to their parties in chariots or palanquins, or on foot with parasols and umbrellas, clothed in fine linen and other costly raiment, drinking wine from goblets of gold, glass, bronze, and porcelain, entertained by bands of music, consisting of the harp, the lyre, guitar, tambourine, double and single pipe, flute, and other instruments, while military ardour was roused by the trumpet and the drum. Cabinet-makers and upholsterers were in demand. They had tables, chairs, sofas. ottomans, stools of all sizes, and bedsteads. Exquisite vases and dishes were made by the potters, and those composed of gold and silver and brass were elegantly shaped, and carved with admirable taste. Not to speak of porcelain, alabaster, stone, ivory, even the earthenware for the common people was adorned with figures of flowers, animals, and men, the latter, no doubt, representing their Washingtons, Jeffersons, Hamiltons, and Websters. The glass-blowers formed bottles of all shapes and sizes. They had beer for the working-classes, as well as wine for the rich. Their cooking was as elaborate as Soyer's, and perhaps as good; but unfortunately they lacked knives and forks, and eat with the formerers, aided occasionally by spoons.

the beam wilitations of the precious stones were exhibited at weights may be ace, London, in 1851, but not more perfect than "The other part Egyptians more than 4,000 years ago. From former, was the ads learned the art of engraving precious

stones. They largely exported vessels of glass and porcelain, and they manufactured linen as fine as muslin. They had the art of dyeing to perfection, and by chemical preparations they brought out various colours on their cloth by dipping it in liquid of one colour. They were skilful in manufacturing the precious metals-drawing gold out into the finest wire, and beating it into the thinnest leaf. There are not more accurate assayists in the National Mint, nor eyes more skilful to detect alloy. With the arts of navigation they were familiar, having barges for merchandise, and yachts for pleasure, and galleys fitted for a broadside with the enemy at sea, the sails being richly painted and ornamented with various devices. They excelled in statuary and portraitpainting, failing only where the knowledge of perspective was required. They had judges learned in the law, but no "Bar." They had doctors paid and held responsible by the state, and the medical profession rose to such eminence, that the healing art of Egypt was celebrated in the surrounding nations.

"There is nothing more certain," says Mr. Hugh Millar, the celebrated geologist, "than that the human species is of comparatively recent origin. All geological science testifies that MAN is but of yesterday." Sir Isaac Newton agreed that almost all the great discoveries and inventions are of comparatively recent origin. "Perhaps the only great discovery or invention that occurs in the fabulous ages of history is the invention of letters; all the others, such as the mariner's compass, printing, gunpowder, the telescope, the discovery of the New World and Southern Africa, and of the true position and relations of the earth to the solar system, lie within the province of the authentic annalist; which-man being the inquisitive, constructive creature that he is-would not be the case were the species of any long gone antiquity."

Steam, gas, and electricity, are discoveries of our own time, which have done more than all that went before to civilise the world. The electric wire now conveys our messages from one end of the Union to the other with inconceivable rapidity. New Orleans and New York are within speaking distance; and the electric cable, which will do more to bind society than all other human ligaments, will probably soon stretch across the Atlantic, animating with one soul the old world and the new. In the midst of these achievements of science, let us not forget what human ingenuity effected in the ages when the world was in its infancy.

What will be the state of the arts four thousand years to come, if the world should last so long, would form a curious subject for speculation. Whether, as many believe, the new elements infused into modern civilisation by Christianity will save it from the fate of its mighty predecessors, is a question which time only can determine. But in discussing it, it is important to remember, that at no former period was a knowledge of the arts and sciences so widely diffused as at present; in no other age was the face of the earth so well known, and the resources of nature so extensively drawn upon for the general good of mankind. Our knowledge and appliances may not, for aught we know, in some departments be so great as those of the ancients, but they are open to all, and are used for the good of all. They are not shut up amongst the members of a caste or hierarchy, and are not dependent for their growth and culture upon the existence of a system. Governments rise and fall, great and powerful orders of men fall into contempt and decay, without impeding for a moment the advance of science. The spirit of caste, the cankerworm of antiquity, and which still exercises its blighting influence in Hindostan, never found footing in the western hemisphere; and any fondness for it, which still lingers amongst the denizens of the old world, is unknown amongst the energetic colonists of America and Australia. If, which we think hardly possible, an excess of riches, or luxury, or any other cause, should ever paralyse the efforts of Americans, Englishmen, or Frenchmen, and consign New York, London, or Paris, to the awful doom of Nineveh or Babylon, the arts, sciences, laws, languages, and civilisation, which have been our glory, will, nevertheless, live amongst the offshoots of our race as long as the world shall last.