PREFACE.

HE empire which man's "invention" has gained for him over nature is, already, great; but what it may be none can tell. The triumphs of science at present realized, may seem but trifles in the future. The human mind enlarges with its conquests, and each new step gives us encouragement to

proceed with another, and we see not where a limit can be placed to the grand dominion man may in the end obtain. A period may arrive when even the Steam-engine may be derided as an imperfect piece of mechanism, and some discovery made that will enable man to wield equal force without the employment of its cumbrous bulk and expensive fabrication. Gas-light, the Printing Press and Printing Machine may, even, pass away into disuse by the institution of superior discoveries; and it may not

be affirmed that any one of the great instruments of present civilization, superb as they are accounted, are unlikely to disappear and give way to other creations of human invention. Electricity, especially, holds such a universe of mysterious power in itself, that we know not to what astonishing purposes it may be applied, even before the lapse of the present century. Printing can already be accomplished by it, and letters written and read in a few moments by those who are hundreds of miles from each other.

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The glory of the future is only to be realized by maturing the grandeur of the present. It is by going on from the point already attained that a more splendid and perfect future is to be reached. Whoever, then, in his youth vows a life-long service to knowledge, or "girds up his loins" with a resolve to become her devoted and untiring disciple, and thus enters into the ranks of science to learn what is now known, increases the probability of science being perfected, inasmuch as new thought and new ardour leads to new invention. • Men's minds are as various as their faces," is an old adage; and every new mind brought within the focal light of science is likely to be enkindled with some new thought by its intellectual beam. what science now requires-young, ardent, never-wearying students, to urge on the glowing process of discovery. Every one who devotes himself to knowledge may become a benefactor of mankind; for whoever increases its empire enlarges human happiness, and helps to quell the reign of evil and suffering.

Students are

Let the young reader, then, strengthen his determination to enlist under the peaceful but ennobling banner of science, by the remembrance that all its great names are held to be more honourable than the military conqueror, because the triumphs of knowledge and invention are gained without bloodshed, and

it is their inevitable tendency to bring war to an end. The communication of mutual advantage by the diffusion of commerce; the perception of such advantage by the exchange of thought, of manufacture, of the comforts and refinements of existence, and by the cultivation of fraternal good-will, are certain results of the increase of science. Who, then, would be slack to enrol himself her disciple while life is young, and there is a prospect of blessing mankind by entering her service? Who would yield to sloth, or dissipate his powers in empty folly, when greater fame may be won, for aught he knows to the contrary, even by his devoted thought, for universal humanity, than has been awarded to Guttemberg or Caxton, Galileo or Copernicus, or even to a Newton, Herschel, Davy, or Watt?

Young reader, the glorious path is open: none can prevent your entering it; there needs but patience and resolution.

Ir is nearly two thousand years since Julius Cæsar first landed from his Roman galley on the English coast. It was on a fine morning in August-just about the time that the ancient Britons were gathering in their corn-harvest-when the Roman legions first saw the British warchariots, with the sharp scythes projecting from their wheels, as they went thundering along the sandy beach below the cliffs of Dover; and great must have been their astonishment, as they gazed from the decks of their high galleys, on the half-naked, long