Angostura, the longitude and latitude of which I have already indicated from astronomical observations, stands at the foot of a hill of amphibolic schist* bare of vegetation. (* Hornblendschiefer.) The streets are regular, and for the most part parallel with the course of the river. Several of the houses are built on the bare rock; and here, as at Carichana, and in many other parts of the missions, the action of black and strong strata, when strongly heated by the rays of the sun upon the atmosphere, is considered injurious to health. I think the small pools of stagnant water (lagunas y anegadizos), which extend behind the town in the direction of south-east, are more to be feared. The houses of Angostura are lofty and convenient; they are for the most part built of stone; which proves that the inhabitants have but little dread of earthquakes. But unhappily this security is not founded on induction from any precise data. It is true that the shore of Nueva Andalusia sometimes undergoes very violent shocks, without the commotion being propagated across the Llanos. The fatal catastrophe of Cumana, on the 4th of February, 1797, was not felt at Angostura; but in the great earthquake of 1766, which destroyed the same city, the granitic soil of the two banks of the Orinoco was agitated as far as the Raudales of Atures and Maypures. South of these Raudales shocks are sometimes felt, which are confined to the basin of the Upper Orinoco and the Rio Negro. They appear to depend on a volcanic focus distant from that of the Caribbee Islands. We were told by the missionaries at Javita and San Fernando de Atabapo that in 1798 violent earthquakes took place between the Guaviare and the Rio Negro, which were not propagated on the north towards Maypures. We cannot be sufficiently attentive to whatever relates to the simultaneity of the oscillations, and to the independence of the movements in contiguous ground. Everything seems to prove that the propagation of the commotion is not superficial, but depends on very deep crevices that terminate in different centres of action. The scenery around the town of Angostura is little varied; but the view of the river, which forms a vast canal, stretching from south-west to north-east, is singularly majestic.