[Footnote 5:  On the data of the text, and allowing sixty-five days in the year for Sundays and high festivals, the yearly profit of one slave to his master would be L. 135 sterling.—­E.]

The quantity of gold thus collected in the Brazils and returned annually to Lisbon, may be estimated, in some degree, from the amount of the royal fifth.  This has been of late computed, one year with another, at one hundred and fifty aroues, of thirty-two Portuguese pounds each, which, valued at L. 4 sterling the troy ounce, make very nearly three hundred thousand pounds sterling; and consequently the capital, of which this is the fifth, is about a million and a half sterling.  It is obvious that the annual return of gold to Lisbon cannot be less than this, though it may be difficult to guess how much more it may be.  Perhaps we may not be much mistaken in conjecturing that the gold exchanged with the Spaniards at Buenos Ayres for silver, and what is privately brought to Europe without paying the duty, may amount to near half a million more, which will make the entire yearly produce of Brazilian gold nearly two millions sterling; a prodigious sum to be found in a country which only a few years since was not known to furnish a single grain.

Besides gold, this country also affords diamonds, as already mentioned.  The discovery of these valuable stones is much more recent even than that of gold, as it is scarcely twenty years since the first were brought to Europe.[6] They are found in the same manner as gold, in the gullies of torrents and beds of rivers, but only in particular places, and by no means so universally spread throughout the country.  They were often found while washing for gold, before they were known to be diamonds, and were consequently thrown away along with the sand and gravel; and it is well remembered that numbers of very large stones, which would have made the fortunes of the possessors, have passed unregarded through the hands of those who now impatiently support the mortifying reflection.  However, about twenty years since, [that is, in 1720,] a person acquainted with the appearance of rough diamonds, conceived that these pebbles, as they were then called, were of the same kind; yet it is said there was a considerable interval between the first stating of this opinion and its confirmation, by proper examination, as it was difficult to persuade the inhabitants that what they had been long accustomed to despise, could be of such amazing importance; and in this interval, as I was told, a governor of one of these places procured a good number of these stones, which he pretended to make use of as markers at cards.  The truth of the discovery was at last confirmed by skilful jewellers in Europe, who were consulted on the occasion, and who declared that these Brazilian pebbles were true diamonds, many of which were not inferior in lustre, or other qualities, to those of the East Indies.  On this being made known, the Portuguese in the neighbourhood of the places where these had been first discovered, set themselves to search for diamonds with great assiduity, and were hopeful of discovering them in considerable quantities, as they found large rocks of crystal in many of the mountains whence the streams proceeded that washed down the diamonds.