The casual observer, or the passing traveller, has but little, therefore, to guide him in his estimate of the population of the country he may be in.  A district that may at one time be thinly inhabited, or even altogether untenanted, may at another be teeming with population.  The wanderer may at one time be surrounded by hundreds of savages, and at another, in the same place he may pass on alone and unheeded.

At Lake Victoria, on the Murray, I have seen congregated upwards of six hundred natives at once, again I have passed through that neighbourhood and have scarcely seen a single individual; nor does this alone constitute the difficulty and uncertainty involved in estimating the numbers of the Aborigines.  Such are the silence and stealth with which all their movements are conducted, so slight a trace is left to indicate their line of march, and so small a clue by which to detect their presence, that the stranger finds it impossible to tell from any thing that he sees, whether he is in their vicinity or not.  I have myself often when travelling, as I imagined in the most retired and solitary recesses of the forest, been suddenly surprised by the unexpected appearance of large bodies of natives, without being in the least able to conjecture whence they had come, or how they obtained the necessaries of life, in what appeared to me an arid and foodless desert.

Captain Grey has observed in other parts of Australia, the same ingenuity and stealth manifested by them in either cloaking their movements, or concealing their presence, until circumstances rendered it in their opinion no longer necessary to preserve this concealment, vol. i. p. 147, he says:  “Immediately numbers of other natives burst upon my sight, each tree, each rock, seemed to give forth its black denizen as if by enchantment; a moment before the most solemn silence pervaded these woods, we deemed that not a human being moved within miles of us, and now they rang with savage and ferocious yells, and fierce armed men crowded around us on every side, bent on our destruction.”

Nor is it less difficult to arrive at the number of the population in those districts which are occupied by Europeans.  In some, the native tribes rarely frequent the stations, in others, portions only of the different tribes are to be found; some belong to the district and others not.  In all there is a difficulty in ascertaining the exact number of any tribe, or the precise limits to which their territory extends in every direction around.  Even could these particulars be accurately obtained in a few localities, they would afford no data for estimating the population of the whole, as the average number of inhabitants to the square mile, would always vary according to the character of the country and the abundance of food.

Upon this subject Captain Grey remarks, vol. ii. p. 246, “I have found the number of inhabitants to a square mile to vary so much from district to district, from season to season, and to depend upon so great a variety of local circumstances, that I am unable to give any computation which I believe would even nearly approach to truth.”