When they reach a certain elevation in the atmosphere, these currents divide and flow, part towards the north and part towards the south; while from the north and the south a flow of heavier and colder air sets in to supply the place of the ascending warm air. Incessant circulation is thus established in the atmosphere. The equatorial air and vapour flow above towards the north and south poles, while the polar air flows below towards the equator. The two currents of air thus established are called the upper and the lower trade winds.

But before the air returns from the poles great changes have occurred. For the air as it quitted the equatorial regions was laden with aqueous vapour, which could not subsist in the cold polar regions. It is there precipitated, falling sometimes as rain, or more commonly as snow. The land near the pole is covered with this snow, which gives birth to vast glaciers in a manner hereafter to be explained.

It is necessary that you should have a perfectly clear view of this process, for great mistakes have been made regarding the manner in which glaciers are related to the heat of the sun.

It was supposed that if the sun's heat were diminished, greater glaciers than those now existing would be produced. But the lessening of the sun's heat would infallibly diminish the quantity of aqueous vapour, and thus cut off the glaciers at their source. A brief illustration will complete your knowledge here.

In the process of ordinary distillation, the liquid to be distilled is heated and converted into vapour in one vessel, and chilled and reconverted into liquid in another. What has just been stated renders it plain that the earth and its atmosphere constitute a vast distilling apparatus in which the equatorial ocean plays the part of the boiler, and the chill regions of the poles the part of the condenser. In this process of distillation heat plays quite as necessary a part as cold, and before Bishop Heber could speak of 'Greenland's icy mountains,' the equatorial ocean had to be warmed by the sun.

ORIENTAL ART AT THE VIENNA

ONL

EXHIBITION.

NLY turn to their show in the arts, and some of them may almost set criticism at defiance. By general consent, and beyond all comparison, the first place must be assigned to Japan. The Japanese does most things unlike the rest of the world. His method of handling his tools is precisely the opposite of ours. He draws his plane toward him, works his saw in the reverse direction, taps with the side of his queer hammer, and handles his quaintly

chased graving tool in a way at which an English workman would stare. Yet, whether he is laying the shingles on the roof of a cottage, or chasing one of those wonderfully elaborate caskets in metal-work, what English workman can approach him? His ideas discover an endless originality; individual impulse, rather than education, seems to inspire his fancy, although it may work according to received traditions of the quaint or beautiful; and, look where we will through a most miscellaneous collection, we can scarcely see a trace of servile repetition. In his pictorial art he can convey a world of expression and suggestion in the very smallest number of touches. Yet when it pleases him to finish, as when he is painting on his delicate porcelain, he is scarcely to be surpassed in harmonious minuteness. As for his colors, you may puzzle out his secret if you can; at least he shows you in an open case the chemicals which, as he professes, form his ingredients. All that can be said is, that none of the numerous attempts at imitation have ever proved to be any thing approaching a success. That strange superiority in color, not only in the tints, but in their management, is to be remarked in every one of the Oriental courts. The silks of China excel even those of Japan, in their bright blues and gorgeous crimsons: while, for softened brilliancy and exquisite delicacy of blending, the Persian carpets are confessedly unequalled. The invariably subdued beauty of these patterns argues something more than great mechanical perfection in the arts of color-making and dyeing. It is proof of a general purity of taste on the part of the Oriental purchasers for whom the fabrics were originally intended; for although many of the best may now be consigned to Europe, the manufacture, precisely as we see it, has been practised from time immemorial; there are carpets in the Exhibition called modern by comparison, although they may date back for a century or so, and these are of patterns exactly similar to the latest ones. In every thing exhibited from China and Persia, the work is almost invariably good and the designs felicitous; although, except in certain specialties, they cannot vie with Japan, yet every now and then one stumbles upon something that is extremely beautiful in art. So much can hardly be said of Turkey. Turkey makes a very imposing display; the Sultan contributed £100,000 towards forming the collection, and some of the great merchants in Constantinople, Smyrna, and elswhere, have apparently done their best to advertise themselves. There is a good deal shown in Turkey, as well as in Tunis, that would have attracted great admiration had there been no Japan and no China to provoke unfavorable comparison. The famous Turkey carpets can scarcely be said to be satisfactorily represented. The very best, beautiful as the texture is, fall far short, even in that respect, of the Persian; while the contrasts displayed in the body of the Turkish patterns are too often disagreeably violent. But for the most part the carpets exhibited are of a very ordinary class indeed.

The inlaid marqueterie and cabinet-work seems rude in design and coarse in execution, if we measure it against the Japenese standards. The carved olive-wood from Jerusalem recalls the pedlers' hawking goods made for sale at the doors of the Holy Sepulchre. Here and there are some exquisite arms among many that are inferior; but even the very best of them are excelled by the Persians. There are graceful shapes in the pottery, but they are not unfrequently marred by defects in the workmanship. There is a great collection of figures in the various national costumes, and the dresses strike one as being somewhat incongruous. On the whole, the only articles in which Turkey may be said to show to decided advantage are some extremely rich furniture stuffs, the choicest of which seem to have been already sold or removed, and the dyed morocco, which, in its vividness of color, shames any thing that can be shown by the West. It must be remembered, however, that the Turk gives almost as many months to the dyeing process as the European allows days. Taste apart, we may perhaps console ourselves for the inferiority which we must confess by repeating that facts like this deliberate process of dyeing furnish the key to much of the Oriental excellence. Time is of no value in the East, and patience and indefatigable perseverance have always been the willing handmaids of their arts and manufactures.- Saturday Review.

OLD TREES.

THER

The

age

of

HERE are but a few very old trees in the world. a tree can be counted by the number of its concentric rings. And some are historic trees, so that there is little difficulty in establishing the age of the oldest trees. It is thought that the average age of oaks and pines is between three and four hundred years. There are, however, well authenticated instances of much greater age. Here are a few of them.

In New England but few trees are more than 400 years old. The Wadsworth oak, at Geneseo, New York, is said to be five centuries old, and 27 feet in circumference at the base. The massive, slow-growing live-oaks, of Florida, are worthy of notice, on account of the enormous length of their branches. Bartram says: “I have stepped 50 paces in a straight line from the trunk of one of these trees to the extremity of the limbs."

The oaks of Europe are among the grandest of trees. The Cowthorpe oak is 78 feet in circuit at the ground, and is at least 1,800 years old. Another, in Dorsetshire, is of equal age. In Westphalia is a hollow oak, which was used as a place of refuge in the troubled times of medieval history.

The great oak at Saintes, in Southern France, is 90 feet in girth, and has been ascertained to be 2,000 years old. This monument, still or recently flourishing, commemorates a period which antedates the first campaign of Julius Cæsar!

Most of the old plane-trees are hollow, their tops being sustained by wood of recent growth. In this respect an exogenous tree resembles a coral-reef, where the vitality and growth are at the surface only.

Of chestnuts, we have the famous one at Tortworth, in Gloucestershire, England, which was a large tree in the reign of King Stephen, and is over 1,000 years old.

The lime or linden, in Europe, is an important tree. Those in the town of Morat are celebrated in the history of Switzerland. One was planted in 1476 to commemorate the defeat of the Burgundians, under Charles the Bold; the other was a noted tree at the time of the battle, and is now near nine centuries old. But, equally famous is the one at Würtemberg, called the "Great Linden," six centuries ago. It is, probably, 1,000 years old, and measures 35 feet in girth. Four and a half centuries ago its branches were supported by 67 columns of stone, now increased to 106, many of which are "covered with inscriptions."

The well-known olive-tree is associated with our most cherished recollections. There is an old one near Nice, 24 feet in girth, regarded by the inhabitants with great interest. Those on the Mount of Olives may be contemporary with the Christian era. They are known to have been in existence in 1217, when the Turks captured Jerusalem.

The ever-green cypress, long celebrated for its longevity, is abundant in the burial-grounds of Eastern nations, and, from its dark, dense foliage, forms an impressive feature of Oriental landscapes. In the Palace Gardens of Granada are cypresses said to be 800 years old; and there is one at Somma, in Lombardy, proved by authentic documents "to have been a considerable tree 40 years before the Christian era." Of this family of trees is our well-known white cedar, specimens of which, exhumed from the meadows on the coast of New Jersey, had from 700 to 1,000 rings of wood solid and fragrant as if of recent growth.

The cedars of Lebanon are often referred to in the Sacred Writings. The present trees are, we believe, seven large ones, with many of smaller growth, situated in an elevated valley of the Lebanon Mountains, 6,172 feet above the Mediterranean. The valley is surrounded by peaks of the mountains, which rise 3,000 feet higher, and are covered with snow. De Candolle supposes the oldest are 1,200 years old, but no sections of their wood have been examined to determine their age. The cedar is known to grow slowly, as does the North American or bald cypress, which we will next notice. This tree is common in the Southern States, and its

rate of growth has been determined. On the Mexican table-lands its growth and antiquity are immense.

The Cypress of Montezuma," near the city of Mexico, is 44 feet in girth, and its age is estimated at upward of twenty centuries. In the church-yard of Santa Maria del Tule, in the Mexican state of Oaxaca, is a cypress which "measures 112 feet in circuit, and is without sign of decay." At Palenque are cypresses growing among the ruins of the old city, whose streets they may have shaded in the days of its pride. By the usual methods, the writer in the North American Review calculates the age of the cypress at Santa Maria del Tule at 5,124 years, or, if it grew as rapidly during its whole life as similar trees grow when young, it would still be 4,024 years old.

The yew has long been used in Great Britain as an adornment of places of sepulture, and is often referred to in English literature: "Beneath these rugged elms, that yew-tree's shade,

Where heaves the turf in many a mouldering heap."

This tree of almost imperishable wood, is indigenous to Great Britain. De Candolle ascertained its rate of growth, and concluded that individual specimens are of great antiquity. There is a yew at Ankerwyke House, older than Magna Charta. It was an old and celebrated tree when King John met the barons at Runnymede, in 1215, and its age is upward of eleven centuries; but the yews of Fountain's Abbey and the Darley yew are from three to five centuries older than this. In Fortingal Church-yard, Perthshire, is a few 18 feet in diameter, through decayed portions of which funeral processions pass on their way to the grave. The age of this tree is estimated at 1,800 years. But of greater antiquity is the one described by Evelyn, which stood in Braborne Church-yard, in Kent. It measured 59 feet in girth, and was believed to be 2,500 years old. This tree, which has long disappeared, was probably contemporary with the founding of Rome. The growth and decline of a great empire was spanned by the duration of a single life.

More immense in bulk, but perhaps not older than these living monuments, are the pines of Oregon and the Sequoias of California. Mr. Douglas counted 1,100 annual layers in a Lambert pine, and 300 feet is not an unusual height for the Douglas spruce. Hutchings states that a Sequoia, which was blown down and measured by him, was 435 feet in length. It was eighteen feet in diameter 300 feet from the ground. Scientific observation has connected with these trees an interest equal to that awakened by their size and age. Our most distinguished botanist, Prof. Gray, has shown that the Sequoias, now growing on a limited area, had formerly a wide distribution, and are lineal descendants from ancestral types which flourished at least as far back in geologic time as the Cretaceous age. The descent has been with modifications furnishing