One notable incident is the continual subterranean roaring heard for a considerable period over twenty-three hundred square miles of Northern Venezuela, a number of years ago, during a violent outpour of lava from the volcano of St. Vincent, an island six hundred and twenty-three miles to the northeast. No motion of the earth was perceptible. It has been supposed that the noise was merely the roar of St. Vincent conveyed through the crust of the earth; but this would raise the question as to why the same noise was not audible at points nearer to St. Vincent? Another suggestion is that the source from which the lava of St. Vincent was derived lay beneath Northern Venezuela; and a fact brought in support of this is, that the great earthquake of Caracas was immediately followed by action at St. Vincent. Similarly, the great eruption of Cotopaxi, in 1744, was attended by subterranean rumbling at Honda, four hundred and thirty-six miles away, and eighteen thousand and one hundred feet lower. Between are the colossal mountains of Pasto, Pichincha and Popayan, with countless valleys and ravines. The cone of Cotopaxi is the smoothest and most symmetrical in the world; perhaps because its eruptions are almost entirely of ashes or fragmentary lava. As no villages lie in its immediate neighborhood, the clouds of ashes have not done so much damage as might be expected. The first sign of an eruption is the melting of the snow upon the cone. Torrents of water sweep down the mountain. Such an outbreak occurring in 1741, after two centuries repose, the amount of snow accumulated may be imagined. The rush of the water tore away blocks of lava, ice and scoria; the plain below was covered with dashing waves. Twelve miles from the mountain the waters still had a velocity of fifty-six feet per second, or about two-thirds of a mile a minute. Escape from such a current would be impossible. Six hundred houses were swept away and one thousand people destroyed. The sides of the cone glowed in the night with a reddish light. Cotopaxi also had a great eruption in 1533, which hurled lava blocks containing one hundred and thirty cubic yards to a distance of nine miles. Such masses would weigh more than two hundred and eighty tons. Such feats will serve to give clearer ideas of the immense power of volcanic action. Perhaps a statement of the force required to raise a column of lava would interest the reader. Lava being about twenty-eight times as heavy as water, a column of it eleven and three-sevenths feet high, and one inch square, would weigh fifteen pounds. Then to raise lava to the tops of various volcanic cones would require pressure or initial velocity as follows: Pressure per Initial velocity Height. square inch. per second.