The elevated bank round the Grand Bassin consists partly of stones thrown loosely together; though porous, the stone is heavy and hard, of a dark grey colour, and contains numerous specks of what seemed to be feldtspath, with sometimes particles of mica and olivine; it is more or less ferruginous, gives a bell-like sound when struck, and in some parts appeared to have run in the manner of lava.  From this description, and the circular form and elevated position of this basin, the geologist will probably be induced to think it the crater of an ancient volcano; and since there are other large holes nearly similar to it, and many caverns and streams under ground in other parts, it may perhaps be concluded that if the island do not owe its origin to subterraneous fire, it has yet been subject to volcanic eruptions, and that the Grand Bassin was one of the vents.

Such were the rivers, lakes, and views which most excited my excursions to the north, the west, and south of the Refuge.  To the east at a league distance, there was, according to my information, a lake called the Mare aux Joncs, from whence rises the R. du Menil; and taking its course northward, joins the R. de Wilhems and at length falls into the Grande Riviere.  At a further distance several other streams were said to rise, some running northward to the same destination as the above, and others south-eastward towards Port Bourbon; but having never visited this part of my limits, I can speak of it only from report, corroborated by a view of the chart.  The country was represented as less inhabited than Vacouas, owing to the want of roads and consequent difficulty of conveyance to the town, upon which the value of land very much depends:  an uncleared habitation* near the Mare aux Joncs was sold for 500 dollars, whilst the same quantity of land at Vacouas was worth six times that sum.

[* The original concessions of land in Mauritius were usually of 1561/2 arpents, of 40,000 French square feet each, making about 1601/2 acres English; this is called un terrein d’habitation, and in abridgment a habitation, although no house should be built, nor a tree cut down; by corruption however, the word is also used for any farm or plantation, though of much smaller extent.]

Upon the high land near the Grand Bassin and in some other central parts of Mauritius, a day seldom passes throughout the year without rain; even at Vacouas it falls more or less during six or eight months, whilst in the low lands there is very little except from December to March.  This moisture creates an abundance of vegetation, and should have rendered the middle parts of the island extremely fertile; as they would be if the soil were not washed down to the low lands and into the sea, almost as soon as formed.  Large timber, whose roots are not seen on the surface, and a black soil, are here the exterior marks of fertility; but near the Grand Bassin the trees are small, though