This dust is driven over a great extent of country, and a gentleman whom I visited, who lived about fourteen miles from Mount Vesuvius, told me that during the great eruption of 1822, his garden was covered with them, to the depth of full six inches. But in more violent eruptions they are carried much further than this. In an eruption of a Volcano in Sumbawa, an island which lies some miles to the East of Java, the ashes were carried to a distance of 270 miles in such quantities as to darken the air, and in another direction they were found 300 miles off. They fell so heavily 40 miles away from the Volcano that they broke into many houses, and rendered them uninhabitable. Quantities of liquid lava are thrown upwards, and shape themselves into nearly the forms of fish by their passage through the air. These are called bombs by the inhabitants, and the fall of them is very justly dreaded, as they come with great violence. The size of the largest of those from which the following picture was taken, was six inches long, two inches and a quarter wide, and one inch and three quarters thick; but there are much larger sometimes. [Illustration] If you should have a chance of examining any of these, you may observe how wisely the living principle, which gives the figure to fish, has been ordained by their Creator to provide the best form to assist their motions, in a medium in which they are suspended, and do not move on ground as the beasts do; seeing that it is precisely the same sort of figure as the laws of inanimate matter impress upon it, when in a yielding state, and being impelled to move under similar circumstances. I must give you a notion of the quantity of lava sometimes sent out in a single eruption. The Volcano called Skapta Jokul, in Iceland, in the year 1794, sent out two great streams, one of which was 50 miles in length, from 10 to 15 in breadth, and the ordinary depth about 100 feet, but in some deep valleys it was more than 500 feet. The other was forty miles long, seven wide on the average, and about the same depth as the first. These streams were not cold in the year 1805, eleven years after they had issued from the earth, so that you may judge how long the hardened lava keeps in the heat. During the eruption in which this immense mass of melted matter was thrown out, twenty villages were destroyed, more than nine thousand persons killed, and an immense number of cattle. The vapour which rises at first in immense clouds, when the eruption slackens, or when it gets out of the reach of the heat, condenses, and mingled with the dust thrown up with it, forms mud, which rushes in torrents down the mountain. These streams of mud are called alluvions, and are very much more dreaded by the inhabitants than the lava streams, because they are so much quicker in their movement.