telescopes I distinguished the details of the rigging and of the hull of the vessel, and recognised it as my father's ship. When we compared our log books we saw that we were then thirty miles apart, namely, seventeen below the real horizon, and many beyond the limit of distinct vision.' A remarkable example of this class of effects occurred during the war with Russia, in May 1854, when, from the deck of the screw-steamer Archer, at that time cruising off Oesel in the Baltic, the whole English fleet of nineteen sail, then nearly thirty miles distant, was seen as if suspended in the air upside down.

The apparent elevation of terrestrial objects, produced by the refraction of the rays of light in passing through the atmosphere, is an effect precisely parallel to well-known astronomical facts. Owing to this cause the stars do not appear in their true place, but at a greater elevation than what belongs to them, while morning and evening, the sun is visible above the horizon when the entire body of the orb is below it. Hence in atmospheric conditions favourable to extraordinary refraction not only are objects apparently altered in their vertical dimensions, so that low coasts assume a bold and precipitous outline, but the visual circle of the spectator is occasionally enlarged in a striking manner. The chain of the Himalaya mountains has been transiently beheld in parts of the plains of Bengal from which it had never been seen before. In July 1798, the whole coast of France from Calais to near Dieppe was brought into view to persons on the beach at Hastings, and seemed only a few miles off, though the nearest points are at least fifty miles apart, and are not ordinarily to be discerned, being hid by the convexity of the earth. So distinct was the spectacle, that the sailors and fishermen were able to point out the places they were accustomed to visit on the opposite shore, such as St Vallery, the Bay, the Old Head, the Windmill at Boulogne, and other spots. The appearance lasted three hours. It occurred at the close of an extremely hot day, when not a breath of wind was stirring, but in the morning, the pennons at the mast-heads of the fishing-boats had shifted through nearly all the points of the compass. This form of mirage is known to seamen as looming, and is very frequently observed by mariners in the polar seas. The Icelanders, who are familiar with the effect under the name of upphillinger, regard it as a presage of good weather. It is an old tradition among them, that Hvidsærk, a mountain in Greenland, and Sriæfells in Iceland, have both been visible at the same time from the middle of the intervening strait, which at the nearest points is about 300 miles in width.

The growth of knowledge has contributed to strip many unusual phenomena of those supernatural attributes which rustic ignorance and polished society once alike assigned to them, exciting perplexity and dismay in village and urban populations. This is the case with reference to the Ignis fatuus (vain or foolish fire'), a luminous appearance occasionally seen in the air immediately overlying shallow, stagnant waters, marshy districts, damp burial-grounds and battle-fields, though science is still at a loss to account for all its incidents. It appears as a pale bluish-coloured flame of varying size and shape, floats in the air about two feet from the ground, and is most frequently observed towards the close of autumn, becoming visible soon after sunset. It sometimes shines steadily through the night, both as a stationary object and one rapidly moving, and is at other times intermittent, or vanishes speedily not to reappear. Superstition in former times regarded the luminous meteor as of demoniacal origin, intended to lure travellers to a miserable death in the swamps by mistaking it for a friendly lamp. Though to some extent still a puzzle to philosophy, it may be referred to phosphurretted hydrogen gas, generated by the decomposition of animal matter, which always ignites spontaneously as soon as it comes in contact with atmospheric air; or to the light carburetted hydrogen gas emitted by decomposing vegetation, ignited by an electric discharge, or by contact with some substance in a state of combustion.

HE productions of the vegetable kingdom are extensively distributed over the surface of the earth, occupying a vast variety of positions for which they are specially constituted, and displaying a boundless diversity of form, colouring, and qualities. Plants flourish and propagate their kind in the bosom of the ocean as well as on land; under the extremes of cold and heat in polar and equatorial regions; on the hardest rocks and the soft alluvium of the plains; amid the perpetual snow of lofty mountains and in springs at the temperature of boiling water; in situations never directly reached by the solar rays, as in the dark vaults of caverns and mines, as well as freely exposed to the influences of light and air. But these diverse circumstances have different species and genera particularly adapted to them. The vegetation which luxuriates in hot climates will not grow in cold, or generally even in temperate regions; and the plants which flourish in the chilling air of high latitudes will

not endure the heat of the tropics. In addition to temperature, much depends upon the humidity or dryness of the atmosphere, and the chemical composition of soils, in determining the indigenous flora which clothes the surface of a country, not only as it respects the species of plants produced, but the texture, size, and entire physiognomy of single specimens. Naturalists usually define by the term species so many individuals as intimately resemble each other in structure and properties, and agree in all their permanent characters. An established species may exhibit new varieties, depending upon local and accidental causes, but these are imperfectly, or only for a limited time, if at all, perpetuated. A genus comprises a number of species similar to each other, but essentially differing in formation, nature, and in many adventitious qualities, from other plants. A botanical tribe, family, group, or order, embraces several genera. The known number of species has been gradually enlarged by the progress of maritime and inland discovery, but owing to large districts of the globe not having been explored, the total number still remains unascertained. It certainly amounts to upwards of 120,000.

The forms of vegetable life are divided into three great classes which differ materially in their structure. 1. Cryptogamous plants, or those which have no flowers properly so called, as mosses, lichens, fungi, and ferns; and are thus distinguished from those which are phænogamus, or flower-bearing, to which the two following classes belong. 2. Endogenous plants, which have stems increasing from within, also called Monocotyledons, from having only one seed-lobe, as the numerous grasses, lilies, and the palm family. 3. Exogenous plants, which have stems growing by additions from without, also called Dicotyledons, from the seed consisting of two lobes, the most perfect, beautiful, and numerous class, embracing the forest trees with most flowering shrubs and herbs.

The cryptogamic or flowerless plants are the most widely diffused, and may be regarded as citizens of the world. They range from the bed of the ocean to the tops of the highest mountains; and are found in the warmest and the coldest climates, being endowed with capacity to endure great extremes of temperature, though most abundant in the colder regions of the globe. Members of the natural order of lichens seem capable of existing anywhere, some growing on the surface of the ground, on stones by the sea-shore, or on weather-beaten rocks, while others attach themselves to the trunks and branches of trees, or paint with patches of green, gray, brown, yellow, and crimson leathery vegetation, the mouldering walls of old castles, abbeys, and churches. Though belonging to the lowest order of vegetable forms these humble plants have no inconsiderable economic value. They yield colouring matter of various hues used in the arts, and some are important for nutritious and medicinal properties. The edible lichens, originally called Tripe de Roche by the Canadian hunters, a designation popularly retained, abundant in the northern wilds, are there used for food in the absence of other resources, as by Franklin and his party, during their perilous overland journey to the shores of the Arctic Ocean, when absolute famine stared them in the face. The well-known lichen, Iceland Moss, Cetraria Icelandica, so serviceable to invalids, occupies a vast extent of the surface in all the northern parts of the world, where also an allied species, familiarly called Mary's Grass by the Icelanders, is an article of daily fare. Another variety, Reindeer Moss, is equally abundant, and forms the only diet of the valuable animal during the prolonged northern winters. Several lichens and mosses, specifically the same, furnish examples of wide dispersion, and accommodation to different circumstances, occurring in regions far apart from each other, at the sea level in northern climes, also on the mountains of Scotland, and in the Himalaya at an elevation of more than 18,000 feet. Great Britain and Australia have species in common, though the great mass of the vegetation in the two districts is remarkably different; and generally speaking, in passing from one part of the globe to another an entirely new flora

is encountered, for if the same genera occur, the species are not identical, while in countries widely separated new genera appear.

The higher orders of vegetable life supply examples of magnificent proportions and great longevity. Some minute fungi appear to live only for a few hours, or at the most a few days. Many herbaceous and flowering plants survive only through a single season, and die as soon as they have ripened their seeds. Others are biennial or triennial in their existence. But several of the forest trees, in a soil and situation congenial to them, flourish for centuries, and far surpass the mightiest empires in their term of duration. The common oak requires upwards of threescore years and ten to reach maturity. It attains its greatest magnitude in periods ranging from one to four hundred years, but lives on to a Methuselah-like age, continuing to vegetate long after the core has decayed, and the trunk been reduced to a complete shell. Numerous examples are on record remarkable for longevity, size, and historical associations. The Salcey Forest Oak, in Northamptonshire, is estimated to be upwards of 1000 years old. It has a girth of 47 feet, and remains a fine vegetable ruin still producing an annual crop of leaves and acorns. But Damorey's Oak, near Blandford, in Dorsetshire, had much larger dimensions, measuring 68 feet in circuit at the base. As this immense trunk decayed it became hollow, and formed a cavity fifteen feet in diameter and seventeen feet high. During the time of the Commonwealth it was inhabited by an old man, and used as an ale-house. The dreadful storm of 1703 reduced the tree to a ruin, but its last vestiges, when sold for firewood in 1755, realised £14. Yew-trees upwards of 700 years old remain at Fountain's Abbey, in Yorkshire, for there is historic evidence of their existence when the abbey was founded in the year 1132; and while the building was in progress the monks resided beneath their shelter. The still surviving chestnut tree at Totworth, in Gloucestershire, was known as a boundary-mark in the reign of King John; and is traditionally carried back to the times of the Saxon Egbert, the founder of the English monarchy.

But these home examples of age and size are far surpassed by foreign ones. The boabab of Senegal, Adansonia digitata, though attaining no considerable height, has a trunk with a diameter sometimes amounting to 34 feet at the base, which therefore gives it a circumference of about 102 feet. Humboldt, on the coast of Venezuela, met with a species of mimosa, Zamang del Guayra, with a hemispherical head formed by the pendant branches, which measured 600 feet round the rim. The banyan-tree of India, Ficus Indicus, remarkable for sending out shoots from its branches which become stems on reaching the ground, occasionally spreads over a space capable of accommodating 7000 persons with shade. But the Californian pine, Wellingtonia gigantea, is the monarch of the vegetable kingdom. Its columnar stem rises to the height of 300 feet, and sometimes more, perfectly straight and erect as a shot-tower, with a circumference ranging from 70 to 102 feet at the base, to which an age of about 3000 years may be assigned. A group of these trees, now known as the Mammoth Trees of Calaveras, was originally discovered by a deer-hunter in the year 1850, on a ledge of the Sierra Nevada, at the elevation of from 4000 to 5000 feet above the sea. It consisted of 123 examples of the largest class, spread over a valleylike area of about 150 acres. One which was felled was 96 feet in circumference at the base, and rose 309 feet from the turf. It was sound to the centre, and was estimated to contain 500,000 cubic feet of timber. Five labourers were required to effect its fall, which extended over more than three weeks, and was accomplished by boring with augurs, and sawing through the intervening spaces. But the tree was so nearly perpendicular as to stand steadfast upon its base after being cut, and had to be brought down by a wedge and battering ram, The trunk remains prostrate, and bears the name of the Fallen Monarch,' and the 'Father of the Forest.' Upon the smooth surface of the stump in the ground,

seven feet high, a round wooden house has been erected, in which dancing parties of more than thirty persons have enjoyed themselves, and theatrical entertainments been given. Near the Fallen Monarch stands the Arbor Vitæ Queen,' 335 feet in height, said to be the loftiest in the grove. These trees were at first supposed to be the only examples of their kind in existence, but other groves and scattered individuals have been met with in the same region. Some Americans, influenced by national feeling, style this genus of giant pines Washingtonia, but the older name of Wellingtonia, given by the first discoverer, is entitled to the preference according to established usage in natural history.

In equatorial and tropical countries, wherever abundant moisture combines its influence with that of the sun's intense external warmth, vegetation appears in its greatest glory and exuberance, not only in relation to the number of individual plants, but also variety of species, and diversity of imposing and attractive forms. The grasses, which in temperate and cold climates are pliant, and seldom grow to any height above the ground, rise rigidly to twenty, thirty, and even forty feet; some reeds ascend to a hundred feet; herbaceous plants attain the size of large shrubs; and the ferns are arborescent. In the three great forest regions respectively, of Brazil, Central Africa, and the Indian Archipelago, the trees consist of majestic evergreens, with differently tinted leaves, scarcely any two adjacent individuals being of the same species or genus, while each shoot up vertically as if striving to escape from the dense throng. Enormous creepers, with brilliantly coloured blossoms, climb their trunks, hang in festoons from branch to branch, or from tree to tree, rendering the woods inpenetrable till the axe has opened a passage. Though crowded with wild animals, birds, and insects, which raise at times a deafening chorus of discordant cries, yet during the heat of the day the intertropical forest is profoundly, even awfully, still. Occasionally there may be heard the well-known crash of a falling tree, and at intervals sounds reach the ear, definite and sharp, like the ring of an axe, for which no Indian or white can account, though referred by the former to the spirit of the woods, which therefore serve to deepen the impression made by the silence of animated nature. Members of the palm family, the princes of the vegetable world,' so-called by Linnæus in allusion to their tall stature and leafy diadems, are eminently characteristic of the earth's hottest zone. Referring to their limited latitudinal range, Von Martius remarks, that the common-world atmosphere does not become these vegetable monarchs. But in those genial climes where nature seems to have fixed her court, and summonses round her of flowers, and fruits, and trees, and animated beings, a galaxy of beauty, there they tower up into the balmy air, rearing their majestic stems highest and proudest of all. Many of them, at a distance, by reason of their long perpendicular shafts, have the appearance of columns, erected by the Divine Architect, bearing up the broad arch of heaven above them; pillars 150 and 180 feet high, crowned with a capital of gorgeous green foliage.' The palm tribe comprises hundreds of species, united by resembling features, though in many respects widely differing, some of which are of large size, and of vast importance to mankind for the nourishing farinaceous food supplied by the fruit in extraordinary abundance. They contribute more than any other trees to impress upon the vegetation of intertropical localities its peculiar physiognomy; and to them the prize of beauty has been assigned by the concurrent voice of nations in all ages. In this highly heated belt of the surface are also produced most of those aromatic, spice, and gum plants, which gratify and excite the appetite of the voluptuary; and from hence are derived many of the most valuable medicines to relieve the ills which afflict humanity.

Many tropical forms pass into the warmer parts of the temperate region, but successively vanish with the decline of temperature consequent on an increase of latitude, and new phases of vegetation are observed. Vividly green meadows abounding with tender herbs