disinterred; since then many others have been obtained from the same neighbourhood, some of them sixty and seventy feet in length. These are all now recognised as belonging to the coniferous family; some of them have even yielded faint traces of annular tissue common to our present forest trees, whence it would appear that even then, there were alternate seasons of heat and cold. It is very probable that these coniferous trees grew upon the higher grounds, whilst those of more succulent texture, as the calamites and others, occupied the swampier and moist parts; consequently the scenery of that early period must have been very different to any that now adorns the face of our old Earth.

Since that period what changes has our old planet beheld; those ancient forest lands have been submerged, and thousands of feet of solid rock has been piled above them. New lands have arisen from the bed of the old ocean, and again subsided; and these alternating agencies have gone on through countless millenniums, until the site of those ancient forests is again standing above the water, its surface completely changed both in its animal and vegetable appearances, and lastly man, the highest work of nature, has appeared to take the whole under his command as the Lord of Creation. Where forests once grew, and the stillness of the primeval world existed, unbroken by any living sounds, except the buzz of the fly, or the creaking of the beetle, is now busy with the din of labour, and the bustle of commerce. The mineral riches deep below, have attracted crowds of human beings above, and founded towns and populous villages, and thus may we trace at present, effects, whose original causes were formed whole millenniums ago. How true, in this respect, are the words of the Poet"There rolls the deep where grew the tree. Oh, earth what changes hast thou seen? There, where the long street roars, hath been The stillness of the central sea."

"The vegetation of the coal period indicates,” says Dr. Hooker, a warmer climate than that which now prevails." The forms of vegetable fossils which are preserved to us in our coal shales are all akin to those which now grow only in tropical climates. For instance, only about 1,500 species of ferns are known, yet of these upwards of 1,200 are confined to the tropics; and although coniferous trees are met with in the coal formation-a class of trees which are spread more or less over the surface of the earth

yet the conifers of the

existing tropical species.

coal strata are mostly those allied to During this period, also, the vegetation

must have been more generally distributed than any particular forms are now. The vegetation of the coal period is known to have extended to 75 degrees, north latitude, for similar fossil ferns are met with in Melville Island, as are found in our English coalfields. To account for these facts it has been supposed that the general temperature of that period was considerably higher than it . is now; it was also supposed that this heat was derived from the interior of the earth, conducted to the surface, and thus so generally diffused as to overcome the difference of the seasons. There are, however, several serious objections to this theory, and on the whole, it is not much held by geologists. The hypothesis of Sir Charles Lyell is that most commonly in vogue, although this does not sufficiently explain all the phenomena.

He supposes an archipelago of islands to have existed in the northern hemisphere at this time, somewhat similar to those in the southern, at present. These islands being entirely surrounded by water, with an atmosphere charged with humidity, and a genial climate, are supposed to be far more favourable to a luxuriant vegetation, than an intense heat; in his own words—“ the northern ocean, at the commencement of the carboniferous era, was divided into basins, varied by islands, and supplied by indunations from extended lands. The agitation on their shores is proved by conglomerates, the amount of indunation from the land is demonstrated by the abundance of argillaceous and arenaceous sediments, plants, and beds of coal; whilst in the more tranquil laboratory of the deeper water, limestone rocks were generated in great abundance."* This theory of Lyell's is the most simple, inasmuch as it accounts for the difference in climate by natural causes; namely, the geographical distribution of sea and land. It is well known, for instance, at the present time, that the position of the Isthmus of Panama affects the climate of England very materially: were that portion of dry land to become submerged, so that the Pacific flowed into what is now the Gulf of Mexico, it would at once annihilate the Gulf Stream which now raises the temperature of England nearly ten degrees, and the ports of Liverpool and London would be blocked by ice many months of the year.

* Lyell's “Principles of Geology.”

As most coal seams possess different qualities, it is very probable that this difference arose from the manner of accumulation of the ancient vegetable debris, or else was dependent upon the original difference of the vegetable components themselves. Thus, in Staffordshire, many beds of coal are deposited one upon the other, with very little intervening earth matters, constituting a mass thirty or forty feet in thickness, so that it may be all worked together; ret the different beds of coal which constitute it may be easily raced.* As many as seventy different denominations of coal are nported into London, and of these forty-five are from the Newastle coal fields. All the different varieties of coal, however, may be ranked under four or five principal heads:-1, caking coal; 2, splint, or hard coal; 3, cherry, or soft coal; 4, cannel, or parrot coal.

1. Caking coal is so named from its fusing or running together in the fire, so as to form clinkers, requiring frequent stirring to prevent the whole mass being welded together. It breaks commonly into short fragments, with an uneven fracture. The Newcastle varieties, and many others from different localities, are caking coals. They often leave many hard cinders, and a dirty dark ash. The caking coal from Newcastle gives out about 8,000 cubic feet of gas to the ton.

2. Splint, or hard coal, is well known in the Glasgow coal-field. It is not easily broken, nor is it easily kindled, although when lighted, it affords a clear and lasting fire. It can generally be got in much larger blocks than the caking coal.

3. Cherry, or soft coal, is an abundant and beautiful variety, velvet black in colour, with a slight intermixture of grey. It possesses a shining resinous lustre, does not cake when heated, has a clean and shaly fracture, is frangible, and readily catches fire. It leaves comparatively few cinders, and its ash is generally white and light. It requires little stirring, and gives out a cheerful lame and heat. The Staffordshire coals belong principally to this variety.

4. Cannel, or parrot coal, is so called in Lancashire because of its burning with a clear flame like a candle, and Parrot in Scotland, from its cracking and chattering when burning. Cannel coal varies much in its appearance. It is found from a dull earthy to a brilliant, shiny, and waxy lustre. It is always compact, and does Phillip's Treatise, Lardner's Cyclopædia.

*

I