AMSTERDAM, an island in the Indian sea. E. Long. 76° 54'; S. Lat. 38° 42'. Part of the crew of an Ameri can vessel, who had been left on this island for the pur pose of collecting the skins of seals and sea-lions, with which its shores abound, were found by the vessel which went out with lord Macartney and his suite to China in 1793. From the marks of volcanic eruption which ap peared in every part of it, Dr Gillan was led to con clude, that this island was produced by subterraneous fire. There arc on its western and south-western sides, four small cones regularly formed, in the craters of which the lava and other volcanic substances are evi dently of recent formation ; and on the eastern side there is a crater, now full of water, of such an astonishing size as considerably to exceed in diameter those of AEtna and Vesuvius. Their intense heat, and the quantity of elastic vapour which continued still to issue through numberless crevices, left no doubt, that the four small cones had been in a state of eruption a very short time before they were visited by Dr Gillan. The soil through out the island is so light and spongy, that the foot sinks deep at every step; and one spot near the centre, ex tending about 200 yards in length, and somewhat less in breadth, is so very soft, that the utmost caution is neces sary in walking over it. Here the heat is so great as to prevent vegetation. From this spot a hot fresh spring is supposed to derive its source, working its way through the interstices of the lava to the great crater, and burst ing out a little above the water which covers its bottom.
The soil here is a kind of mud or paste, composed of the ashes moistened by the stream which constantly rises from below; when this mud, which is scalding hot, is removed, vapour issues forth copiously, and with violence. All the hot springs, except one, are brackish. One spring, which issues from the high ground and ridges of the crater, instead of boiling upwards, like the other, through the stones and mud, flows dow a wards in a small stream, with considerable velocity ; its temperaturo did not exceed 112 degrees; it was a pretty strong chalybeate ; the ochre which it deposited had I hi• sides of the i.od, iron, o issued], and of the cavity into %%hid, it I'll; yet the seamen made use of it a uhout the iucouv unieu,e. island is upwards of four miles in length, about two miles and a half in its greatest breadth, and eleven miles in circumference ; comprehending a surface of 51.30 acres, nearly the w hole of a hid, with a fertile soil. On the cast side, the great ( later forms ,! harbour, the entrance to which is deepening annualk and might, without much labour, he made lit for the re • c•ption of large ships. The tides flow in and out, in the direction of south-east by south, and north-cast IA north, at the rate of three miles an hour ; and the watt r is right or ten fathoms deep, almost close to the edg( of the crater. On cNur• other side the island is inac cessible. (pc)