On first arriving at Sydney from South America, I was much struck with the strange contrast its extensive and at the same time youthful appearance presented to the decrepit and decaying aspect of the cities on that continent. We had then been visiting colonies and settlements founded centuries ago, by a nation at that time almost supreme in European influence, and planted with every circumstance of apparent advantage upon the shores of a fertile and luxurious continent given by the immortal Genoese to the crown of Spain. We had found them distracted by internal commotions, disgraced by ignorance, debased by superstition, and defiled by slavery. COLONISATION. In Sydney we beheld with wonder what scarce half a century had sufficed to effect; for where almost within the memory of man the savage ranged the desert wastes and trackless forests, a noble city has sprung as though by magic from the ground, which will ever serve both as a monument of English enterprise, and as a beacon from whence the light of Christian civilisation shall spread through the dark and gloomy recesses of ignorance and guilt. The true history of our Australian possessions; the causes which have led to their settlement; the means by which they have been established; the circumstances by which they have been influenced; and the rapid, nay, unexampled prosperity to which they have attained; present some of the most curious and most important laws of colonisation to our notice. Without attempting so far to deviate from my present purpose as to enter here on a deduction from the data to which I have alluded, it cannot be denied that, in the words of an eloquent writer in Blackwood, "a great experiment in the faculty of renovation in the human character, has found its field in the solitudes of this vast continent: that the experiment has succeeded to a most unexampled and unexpected degree: and that the question is now finally decided between severity and discipline." What else remains, what great designs and unfathomed purposes, are yet reserved to grace this distant theatre, I pause not now to guess. The boldest conjecture would probably fall very far short of the truth. It is sufficient for us to know that Providence has entrusted to England a new empire in the Southern seas. Nor can we doubt that there as elsewhere throughout the various regions of the habitable globe, the same indomitable spirit which has achieved so many successes, will accompany those whom heaven has appointed as pioneers, in that march of moral regeneration and sound improvement long promised to the repentant children of earth. QUARANTINE ESTABLISHMENT.