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CANALS.

The most stupendous in the world is a canal in China, which is said to pass over 2,000 miles, and to 41 cities; commenced in the tenth century. The canal of Languedoc, which joins the Mediterranean with the Atlantic Ocean, was completed in 1681. That

of Orleans from the Loire to the Seine, commenced in 1675. That between the Baltic and the North Sea at Kiel, opened 1785. That of Bourbon, between the Seine and Oise commenced 1790. That from the Cattegat to the Baltic 1794-1800.

The great American Erie Canal, 363 miles in length, was commenced in 1817. That from Amsterdam to the sea 1819-25. The first canal made in England was by Henry I., when the river Trent was joined to the Whitham, A.D., 1134.

The most remarkable canals in Great Britain are :—

In England there are 2,800 miles of canals, and 2,500 miles of rivers, taking the length of those only that are navigable; total, 5,300 miles. In Ireland there are 300 miles of canals; 150 of navigable rivers; and 60 miles of the Shannon, navigable below Limerick; in all, 510 miles.

THE

Coal Measures of Great Britain.

WERE we to choose a subject for comment on account of its greater importance, besides the primary necessaries of life, food and clothing, it would be that of Fuel. Its possession is absolutely necessary to the most common comforts of life. So useful has it been to man, in the different stages of his civilisation, that the ratio of its use would form no mean index to them. From the savage Fuegian who eats his flesh raw and uncooked, to the polished European who employs fuel in almost every occupation, this fact would be found universally true; consequently we might expect that where it was most abundant, all other things being equal, that country would become the greatest, and the most important. This is greatly true of our own country; taking the small area of our island into account, there is no country in the world more blessed in the possession of that fossil fuel termed "Coal," than our own. Situated as it is in the most favourable part of the temperate zone, and harassed neither by tropical heat nor by polar cold, its inhabitants are the most favourably placed for the development of their mental and physical faculties; so that every natural fact which had turned up would have served as a subject for their employment: much more then, might we expect great results from the possession of great facts. And in what greater facts can England pride herself than her vast coal-fields, and their often accompanying ores of metal? South America has rejoiced in the possession of gold and silver ores, and their discovery has filled the coffers of nations; but, in few instances, have they really blessed a country, or assisted poor humanity in its onward progress. Not so, however, with our loved Island; her

mineral treasures, dug deep from the bowels of the earth, have helped to make her great, and to develope the genius and hardihood of her sons; and have thus served to render her name illustrious, even in unpenetrated lands. Had the geology of England been different to what it is, either more granitic or more tertiary, the world would have been different in its moral aspect too: England would never have radiated her greatness or her morality to other lands, and supplied their lackings from her abundance. Providence has seemed to bless the Anglo-Saxon race everywhere. In the temperate regions of North America, another of the richest countries in mineral wealth, colonies of her sons have been located, and they have by no means suffered the name to tarnish. The same may be said of Australia, in the temperate zone of the southern hemisphere; and thus have the inhabitants of a little island-scarcely perceptible in a tolerable sized map of the globe, attained to one of the proudest and most honourable positions among the nations of the earth.

That portion of England's geology which has more especially helped to make her what she is, is the carboniferous or coal formation, which is better developed in Great Britain than in any other country in the world. Although a great amount of ignorance concerning this interesting formation prevails, it is not because there is lacking information upon it, but perhaps chiefly because most of this information is scattered through the transactions of different geological (and other scientific societies. An excellent treatise has appeared upon the coal-fields of Pennsylvania, by Professor Rogers, but no regular work on the carboniferous formation of Great Britain has yet been compiled, although much wished for, and required. The memoirs of the geological survey have done much to elucidate the phenomena of a part of it. But apart from its rich stores of fuel, which makes it so valuable to man, the carboniferous formation is also one of the most interesting in the whole geological series. Its different sub-divisions, its alternating strata, some of them of estuarine origin, others of lacustrine, and most of marine, are each characterised by different forms of organic remains. The mechanical portion of its geology is also most interesting and valuable; the different dykes and faults giving evidence of extensive convulsions which have contorted and separated stata, thousands of feet in thickness; not to speak of the interesting problems which open out to us in its fossil botany.

In fact, to take up this subject properly, it would not only be a labour of years, but would likewise fill volumes with its descriptions.

Although we have selected this subject for a brief comment, it is evident that our space is not sufficient to do it justice, even if we were able; it requires a master-hand, the labours, learning, and life-time of another Murchison, properly to arrange and systematise it. The following pages, however, contain a brief digest of this most important portion of our geology.

A person commencing this study for the first time, is often astonished by the immense periods which must be allowed for its phenomena to have taken place. The whole of the stratified rocks, which have been formed by processes similar to those now going on, viz., the simple wasting of land, by rivers and seas, and its depositions on the bed of the ocean, are upwards of ten miles in thickness: the time which has elapsed in their formation must consequently be immense. The rocks of the coal measures alone are above fifteen thousand feet in thickness. Very often evidence of the vast tracts of time, which have been occupied, may be traced in the structure of the rocks themselves. A stratum of rock, only a few inches in thickness, will often contain fossil remains of individuals in every stage of their growth. In some of the shale-beds of the coal measures the laminæ are often no thicker than a sheet of pasteboard, for whole yards in depth, and yet, upon each of these thin sheets the impressions of numberless organic remains may be seen. Not unfrequently it happens that, if the stratum be tolerably thick, the upper part will contain fossils altogether different from those beneath; the old races have lived and died away, and other beings have occupied their places; all during the formation of a stratum of limestone, or a bed of shale, of only a few feet in thickness. Again, according to Boussengault, luxuriant vegetation at the present day takes from the atmosphere about half a ton of carbon per acre annually, or fifty tons per acre in a century. If fifty tons of carbon, of the specific gravity of coal, be spread evenly over the surface of an acre, it would, according to Humboldt, at the most only form a layer of about half an inch in thickness. It appears, therefore, that if all the carbon taken from the air, was preserved in the form of coal, our most luxuriant vegetation would make but half an inch of coal in a century but, in the coal measures, the aggregate thickness of the