VOLGA 
Those places on the earth's surface where subterranean fires have formed 
openings are called volcanoes. A volcano is a sort of pipe, or chimney, 
which occasionally pours forth streams of melted rocks or lava, showers 
of ashes and sand, torrents of water and mud, and jets of steam and gas. 
The general form of a volcano is that of a regular cone, at or near the top 
of which is a circular pit, or cavity, in the form of a funnel, called the 
crater. The conical form is occasioned by the substances thrown out of 
the crater lodging on all sides round about the opening. 
Volcanoes are very numerous, and are found in various situations ; some in 
plains at a small elevation above the level of the sea, others in the midst of, or 
near to mountain ranges. The most remarkable volcanoes in Europe are, Etna 
in Sicily, Vesuvius in Italy, and Kekla in Iceland. Of these the eruptions 
have been frequent, about fifty being recorded of Etna ; while within little more 
than a century, Vesuvius has had eighteen eruptions. There is no record of 
Vesuvius as an active volcano till the year a. d. 70, up to which time the ancient 
crater presented a slight circular hollow, the sides of which wei*e overgrown 
with wild vines, and the outside of the cone was well cultivated. In that year, 
however, there was a dreadful eruption, which destroyed three towns, Stabise, 
Herculaneum, and Pompeii. Etna, in 1699, poured out from a long rent in its 
flank a stream of lava, which, in its course to the sea, destroyed fourteen towns 
and villages, some of which contained three or four thousand inhabitants. 
The volcanoes of America are very numerous, and of great size. Several of 
the loftiest mountains of the Andes are active volcanoes, the eruptions of which 
produce terrible earthquakes. Cotopaxi, which rises to an elevation of sixteen 
thousand eight hundred feet above the sea, is an active volcano. One of the 
most remarkable is the volcano of Jorullo, represented in the above engraving. 
It is situated to the west of the city of Mexico. The formation of this volcano 
does not date farther back than 1759. Up to that time a fertile, well-cultivated 
plain existed on the spot. In June 1759 thundering noises where heard under- 
ground, accompanied by frequent shocks of earthquakes, which continued during 
fifty or sixty days. In September the inhabitants hoped that these fearful 
phenomena were at an end; but on the 29th of that month they were renewed, 
and a space of about four square miles rose up, like an enormous bladder, to 
the height of above five hundred feet. Those who gained the neighbouring 
mountains saw flames shoot up from a surface of a square league in extent, and 
huge masses of ignited rock hurled into the air through a dense cloud of ashes. 
The surface of the ground appeared like a troubled ocean. The waters of two 
streams poured into the burning chasm, and this seemed to increase the fury of 
the flames. Thousands of small burning cones, of from six to eight feet high, 
issued from the surface ; and in the midst of these hornitos, or ovens, as they are 
NOES. 
called, six vast mountain masses arose to a height varying from three hundred 
to sixteen hundred and ninety feet above the former plain. The highest of these 
is the volcano of Jorullo, which is constantly burning, and has thrown out a 
vast quantity of ashes and lava, mingled with fragments of rocks. The ashes of 
this eruption were scattered to a distance of one hundred and sixty miles. The 
eruptions of the Jorullo continued till February 1760 without ceasing, but they 
have since become less frequent. 
An eruption of Vesuvius begins with a violent crash, if not with an earthquake, 
and the crater is broken open by the invisible vapours within. A loud, hollow, 
rumbling noise is heard, interrupted by violent explosions. The white smoke 
which previously issued from the cone darkens in colour, and at length becomes 
quite black, rising higher and higher above the summit. "With this column is 
thrown up an immense quantity of solid matter, called scoria, sand, and ashes ; 
large masses of rock are also thrown up with a crashing noise, many of which, 
bursting asunder, produce a shower of splendid sparks. The appearance of this 
column by night is extremely grand and awful; the light issuing from the lake of 
burning lava in the crater illuminates the column, and the masses of glowing 
rock rising and sinking within it are more distinctly seen. 
After a time the larger pieces of rock cease to be thrown out, but the quantity 
of ashes is much increased : the column of smoke rises higher and higher, and the 
upper part expanding on all sides, gives it the appearance of a kind of pine-tree 
common in Italy ; on which account the column of smoke towards the close of the 
eruption is called th&Jpmei* ''This beautiful phenomenon is an object of admira- 
tion even in the day-time, but in the dark night it presents one of the most im- 
pressive scenes of beauty which nature can afford. The column of smoke is 
converted into a magnificent column of fire by the reflection of the light from 
the crater, and its interior is literally dotted by numberless shining points of great 
splendour, which are the many millions of glowing grains of sand and ashes rising 
and falling continually. In the column, but still more frequently in the cloud 
above it, flashes of forked lightning are seen every moment in all directions, and 
are accompanied by thunder. After this has lasted for some hours, the cloud 
imperceptibly vanishes and the column of ashes gradually disappears. The 
eruption is at an end." 
The force with which volcanoes shoot out stones, sand, &c. is enormous. The 
dust of the volcano of St. Vincent was carried more than two hundred miles to 
the east of that island. It is stated that Vesuvius has projected large stones 
three thousand six hundred feet above its summit, and Cotopaxi has been known 
to hurl a rock calculated to contain two hundred tons to a distance of rather more 
than ten English miles. 
PUBLISHED UNDER THE DIRECTION OF THE COMMITTEE OF GENERAL LITERATURE AND EDUCATION, APPOINTED BY THE 
SOCIETY FOR PROMOTING CHRISTIAN KNOWLEDGE. 
No. 30.] 
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