SOURCE OF VOLCANIC FIRE.

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noes unchanged by fire ; which proves thatthe source of heat was deep below' the range*of these rocks: they have been merely drivenup by the subterranean explosion, which forceda passage through them.

From the various phenomena which vol-canoes present, we may with probabilityinfer that the internal part of our planet is inan igneous state, however difficult it may beto explain in w hat manner this heat is gene-rated and confined. In every department ofnature,our inqui ies are terminated by ultimatefacts, beyond which further research becomesvain. The constant generation and emission oflight from the surface of the sun is more inex-plicable and surprising than the constant gene-ration of heat in the centre of the planets; butwe cannot refuse our assent to the fact, thoughit is far beyond the power of the human mindto conceive by what means the particles oflight are propelled through space with suchastonishing velocity. We are too apt to mea-sure natural operations by their coincidencewith the received system of philosophy, andto make our own ignorance the standard of

O

ii 2 truth.