[_Or sphere on sphere_. l. 143. See additional notes, No. VII.]


"YOU from deep cauldrons and unmeasured caves
150 Blow flaming airs, or pour vitrescent waves;
O'er shining oceans ray volcanic light,
Or hurl innocuous embers to the night.--
While with loud shouts to Etna Heccla calls,
And Andes answers from his beacon'd walls;
155 Sea-wilder'd crews the mountain-stars admire,
And Beauty beams amid tremendous fire.


[_Hurl innocuous embers_. l. 152. The immediate cause of volcanic
eruptions is believed to be owing to the water of the sea, or from
lakes, or inundations, finding itself a passage into the subterraneous
fires, which may lie at great depths. This must first produce by its
coldness a condensation of the vapour there existing, or a vacuum, and
thus occasion parts of the earth's crust or shell to be forced down by
the pressure of the incumbent atmosphere. Afterwards the water being
suddenly raised into steam produces all the explosive effects of
earthquakes. And by new accessions of water during the intervals of the
explosions the repetition of the shocks is caused. These circumstances
were hourly illustrated by the fountains of boiling water in Iceland, in
which the surface of the water in the boiling wells sunk down low before
every new ebullition.

Besides these eruptions occasioned by the steam of water, there seems to
be a perpetual effusion of other vapours, more noxious and (as far as it