of the seismic bands; that is to say, along the axial lines of nearly all the great mountain ranges upon our globe.
But that the intensity of these forces is greater by much, at some points along these axial lines, than at others; that the intensity remains constant nowhere, but shows itself paramount at certain points, for immense periods of historic time; that it wanes, and again waxes powerful, at the same point, (Vesuvius in volcanoes, Antioch in earthquakes, for example, both long in repose, again long in intense action); and that the points of greatest intensity at any given time, have been found to shift along the axial lines; now most active here, then further on, but slowly moving, and in the same direction, (or expanding in both directions, as Humboldt says of the new Madrid band,) in the same cycle of time.
Can we possibly, with these facts before us, rest in the commonly-received vague notion that volcanic and seismic action have their common origin, in an all-pervading and perfectly uniformly-distributed, planetary temperature, increasing everywhere alike, by a uniform hypogeal increment? Can we remain satisfied with the pompous, but almost empty phrase, (although sanctioned by a Humboldt,) that "they are due to the reaction of the interior of our planet upon its exterior;" if the only meaning that we are to attach to the phrase is, that the reaction is that, of a universal ocean of heated or of molten matter, everywhere to be reached within some certain limit of depth? Do not the facts rather all point towards some cause that has been long present, and is so now, and still in action wherever mountain ranges have been elevated, as well as wherever volcanic vents have thrown or are throwing up, their lines
