The discovery of gold in the new continent has thrown the country into a state which well merits examination. The same circumstance in California was no interruption to progress of any kind. It merely peopled a desert, and opened a trade where there was none before; while in Australia it finds an established form of civilisation, and a commerce flowing in recognised channels. It is an interesting task, therefore, to trace the nature of the influence exercised in the latter country over old pursuits by the new direction of industry; and it is with some curiosity we open a mercantile circular, dated Sydney, 1st November 1851. This, we admit, is a somewhat forbidding document to mere literary readers; but we shall divest its contents of their technical form, and endeavour, by their aid, to arrive at some general idea of the real state and prospects of the colony. Up to the middle of last May, the colonial heart beat high with hope. Trade was good; the pastoral interests were flourishing; the country properties, as a matter of course, were improving; and the introduction of the alpaca, the extended culture of the vine, and the growth of cotton, appeared to present new and rich sources of wealth. At that moment came the discovery of the Gold Fields; and a shock was communicated to the whole industrial system, which to some people seemed to threaten almost annihilation. The idea was, that gold-digging would swallow up all other pursuits, and the flocks perish in the wilderness from the want of shepherds. Nor was this altogether without foundation; for the stockholders have actually been considerable sufferers: all the industrial projects mentioned have been stopped short; and the gold-diggings still continue to attract to themselves, as if by a spell, the labour of the country. The panic, however, has now subsided. It is seen that the result is not so bad as was anticipated, and hopes are entertained that the evil will go no further. A stream of population, it is thought, will be directed to Australia from abroad, and the labour not demanded by gold may suffice for other pursuits. Up to the date of the circular, the value of gold shipped for England from New South Wales had been L. 217,000, and it was supposed that about L. 130,000 more remained at Sydney and in the hands of the miners: 10,000 persons were actually engaged in mining, and 5000 more concerned otherwise in the business; and as the result of the exertions of that multitude, the amount of gold fixed arbitrarily for exportation during the next twelve months, is L. 2,000,000.