and more compact form of the same fossil which, in its other modifications, we call naphtha, petroleum, tar, or asphalte. It is found in beds of lignite or brown coal in almost all places where amber occurs; and appears, in fact, to be but the bituminised wood of those trees of which amber is the fossilised gum. It is of an extremely black colour, and susceptible of a fine polish; and as it is easily cut and turned, it is much used for beads, figures, and other ornaments. Imitations of jet are common; but the genuine article may be readily detected by its lightness. Specimens of all the above-named varieties of mineral pitch are to be seen in the case under notice, together with some other bitumens, such as the elaterite, or elastic bitumen of Derbyshire and Fifeshire; the dapeche, an inflammable fossil substance, not unlike India-rubber, found by Humboldt in South America; the hatchetine, a bitumen found in South Wales; the scheererite, the hartite, &c.

Coal. Of this important mineral, with which it so happens that the classification comes to a close, only as many specimens are given as will illustrate the different varieties that it assumes. The most conspicuous of these are the black coal and the brown coal or lignite, both of which are nothing else than ancient vegetable matter which, having been amassed in peculiar circumstances at certain depths below the earth's surface, has in course of time lost its vegetable character, and become more or less fossilised. Were one of our forests suddenly overthrown, and buried under such a pressure of superincumbent material as would crush the trunks, branches, leaves, and underwood together during the process of decay, the result, after the lapse of a certain number of ages, would be a bed of coal. Peat-mosses are to be regarded, therefore, as illustrations of the first stage of the passage of vegetable matter into coal; brown coal or lignite, in which the forms of the component vegetables-the trunks, the branches, &c.-are still discernible, is an illustration of the same process a little farther advanced; and black coal exhibits the process completed. While, however, all geologists are agreed that coal is but the fossilised accumulation of vegetable matter, there are subordinate differences of opinion as to the manner in which such accumulations took place. Some contend that the component parts of the coal-the trees, the ferns, the grasses, &c.—grew up and accumulated in huge forests or jungles, as in some parts of the world at the present day, each year's growth adding a new supply of decaying matter to the soil; that thus peat-mosses were formed such as we now see; and that these peat-mosses became submerged and covered over with layers of sand, mud, &c. which, hardening into rock, shut down the vegetable matter, and compelled it, in the process

Others be

of chemical alteration, to assume the form of coal. lieve that coal-beds were originally jungles at the mouths of rivers into which miscellaneous masses of foreign matter, such as sand, mud, and vegetable substances, were drifted from higher lands, the whole at last becoming covered up. In whatever way coal was formed, one cannot but admire the care with which nature, in these rough processes that were going on in the early world, was storing up for its future inhabitants such wealth and abundance of a most necessary material. Ages ago, ere yet a man stood on the planet, its surface was clothed with vegetation; man then came, and the vegetation was covered up in the earth; and now at last, after some six thousand years, he has learned to dig it up again, and to use it as fuel for his fires, his furnaces, and his steamengines. In Britain coal first began to be used for fuel in the twelfth century; and from that time the use of it has increased and extended, until now there is hardly a spot of the earth where coal is not dug for or imported. It is found more or less extensively in France, Spain, Belgium, Germany, India, China, the East Indies, Australia, New Zealand, the United States, Nova Scotia, Chili, Peru, Panama, and some of the Pacific Islands. In Britain the principal coal-fields are those of Northumberland and Durham, Lancashire, Stafford, and the Scottish Lowlands. From the various collieries or coal-mines in these districts about 30,000,000 tons of coals are at present annually raised, of which about 3,000,000 or 4,000,000 are exported to other countries, and the rest consumed within the island. Such an annual drain from the bowels of the earth must in course of time produce a sensible diminution in the quantity of coal in the island; but the supply of coal over the whole globe is so vast, that, the means of carriage remaining the same, there is no fear of a scarcity for ages to come. It is the black coal that is chiefly used for fuel, brown coal, or lignite, being less valuable. The principal kinds of black coal used in this country are thus distinguished-caking coal, such as is found at Newcastle, a highly bituminous sort, which emits much smoke, and cakes while burning; cubic coal, which is also bituminous, but does not cake; splint or slate coal, which is less bituminous, yields an intense heat, and leaves little ash; and cannel coal, a compact shining variety, which burns with a clear flame, and leaves a whitish ash. These varieties are found in different localities, are used for different purposes, and fetch different prices. All of them are easily to be distinguished from the anthracite or blind-coal (See Carburets), which is non-bituminous, has a semi-metallic lustre, and burns without smoke. Some compact varieties of cannel coal admit of being cut or turned; and in the museum there are to be seen busts of Henry VIII. and

his daughter Lady Mary cut out of masses of this common native mineral.*

II.-BOTANICAL SECTION.

This section comprises two rooms in the museum adjacent to the Mammalia Saloon; but as these rooms are not open to the public, owing to the peculiar nature of their contents-which are, for the most part, of a kind that would suffer from exposure-they are not mentioned in the catalogue, nor would a casual visitor to the museum be aware of their existence, or even of the fact that the museum contained a botanical section at all. Students of botany, however, or persons having any special object in view, are admitted to the Botanical Rooms on proper application being made to the authorities of the museum; and for the public in general such a brief account of their contents as we shall here give will doubtless be sufficient.

The first expressly botanical author among the ancients was Theophrastus, the pupil and successor (B. C. 324) of the great Aristotle. The total number of plants known and registered in his time was 500, which was probably as many as could be easily collected in any single locality in Greece. As plants were then sought purely with a view to their medicinal or horticultural uses, few additions were made to this list, and the entire number of which the ancients bequeathed a register to the moderns did not exceed 700. After the revival of natural science in the middle ages, the study of botany was prosecuted with ardour; and the area over which observers could extend their researches having been gradually enlarged, the result since that time has been a wonderful extension of the botanical catalogue. The successive stages of this result are presented by a recent French author, in a very instructive form, as follows:

:

in 1546 enumerated 879 plants.
in 1570

Lonicer

Lobel

Dalechamp in 1587

Gaspard Bauhin in 1596

Tournefort
Ray

Linnæus

in 1694

in 1704

in 1762

2,191

2,751

6,000

10,146

18,655

8,551 species; the apparent decrease arising from the reduction which Linnæus's system of classification

* In connection with the subject of this section, see essay of Berzelius entitled 'Attempt to Establish a new System of Mineralogy,' translated from the Swedish under the superintendence of Dr Thomson of Glasgow in 1814; the same essay in French, enlarged and published by Berzelius himself some years later; also 'Phillips's Mineralogy,' 'Jameson's Mineralogy,' treatise on Mineralogy in the Encyclopædia Metropolitana,' and sheets on Mining and Metallurgy in Chambers's Information for the People.'

effected in the number of species, notwithstanding that the whole number of individual plants known had enormously increased. Persoon in his Synopsis Plantarum,' published in 1805-7, enumerated

6

Steudel, in the first edition of his 'Nomenclator Botanicus,'

26,000 species.

50,649

88,000

95,000

Arguing from the law of increase exhibited in this table, in connection with the estimated extent of the earth's surface that remains yet to be botanically explored, an attempt has been made to arrive at an approximate conclusion as to the total number of vegetable species existing on the globe. Some limit the number to 150,000, others raise it as high as 300,000, but any such supposition can be at best but a guess. The time, however, may not be far distant when every existing species of the vegetable kingdom shall be accurately known and registered; so that on whatever spot of the earth's surface a botanist lives, he shall have the means of becoming acquainted with the vegetation of the whole. The obvious mode of classifying plants, or any other substances requiring classification, is to arrange them so that all those most resembling each other shall be placed together. This, properly considered, is the essential and only principle of classification, and logicians have taken care to furnish a set of terms corresponding with it. Thus the word class is the strict scientific denomination for a number of substances resembling each other in certain broad leading features; the term order is employed to include such as are still more closely allied; a genus consists of those resembling each other in a still greater number of particulars; and a species defines a still closer type or resemblance, slight deviations from which are designated varieties.

All botanists have followed this general principle of classification, and have adopted, with certain modifications, the logical terms consecrated to it; but they have differed materially from each other as regards the precise parts or properties of plants in which we should seek for their mutual likenesses. Thus it would be possible to found a classification on the mere circumstance of the colour of the flowers of plants; classing all the blue-flowered plants, all the white-flowered plants, all the red-flowered plants, &c. together. But such a classification would obviously be clumsy in the extreme-plants that are closely allied, or almost identical, often having flowers of different colours. In a similar manner, any attempt to classify plants by any other single peculiarity in their aspect would be found useless. The business of the botanist is to find out, if possible, what peculiarity of the structure of a plant, or what assemblage of properties in it, is the essential thing in the

constitution of that plant-what peculiarity of structure, for example, or what assemblage of properties in a rose constitutes it a rose-and on this discovery to found his classification.

The early botanists were content to classify plants according to their more obvious resemblances, and it was not till near the beginning of the eighteenth century that a scientific system was attempted. In 1694 the French botanist Tournefort proposed a classification founded chiefly on differences in the corolla or flowerpart of the plant; and about the same time our countryman, Dr John Ray, a man of great capacity, and who did more for the progress of natural science than almost any other man of his age, originated two most important botanical ideas-that of the division of all plants into FLOWERING and FLOWERLESs plants; and that of the distinction of flowering plants into the two great denominations of monocotyledons, or such as have one cotyledon or seed-lobe -as, for instance, the cocoa-tree; and dicotyledons, or such as have two cotyledons or seed-lobes-as, for instance, the oak or beech. But the labours of both these naturalists were superseded by those of the celebrated Swede, Carl Von Linné, more commonly known by his Latinised name of Linnæus. Born in 1707, he began the study of the natural sciences about his twentieth year, and from that period till his death in 1778 his whole attention was devoted to them. Amassing and revising all the knowledge that his predecessors had collected, and enlarging it by his own observations, he also succeeded in establishing many radical changes in the mode of prosecuting the various branches of natural history, especially botany. Of the system which he proposed for the classification of plants—a system usually called the Linnæan, but sometimes also the Sexual or Artificial System of Classification— the following is a brief outline :

Plants reproduce themselves or propagate their species by certain organs adapted for the purpose. In the vast majority of plants these organs assume the form of flowers, and constitute a conspicuous portion of the general development of the plant; in some plants, however-as in ferns, mosses, lichens, sea-weeds, &c.-the reproductive agency is of a different kind, and has no such manifestation. Hence the first great division of the vegetable kingdom is into flowering plants, called also phanerogamous—that is, openlymarrying plants; and flowerless plants, called also cryptogamous— that is, secretly-marrying plants. Of the 8551 species of plants that composed the entire botanical catalogue of Linnæus, 7728 were phanerogamous, and only 825 cryptogamous. In order farther to classify the former, he went on to observe the differences that were discernible in their respective flowers. The flower of a plant usually consists of several distinct parts-the calyx, or leafy cup