“So great is the heat within the Earth, that in Switzerland, and other countries where the springs of water are very deep, they bring to the surface the warm mineral waters so much used for baths and medicine for the sick; and it is said, that if you were to dig very deep down into the Earth, the temperature would increase at the rate of one degree of the thermometer for every 100 feet; so that, at the depth of 7000 feet, or one mile and a half, all the water that you found would be boiling; and at the depth of about ten miles all the rocks would be melted. * * * A day will yet come when this earth will be burned up by the fire. There is fire, as you have heard, within it, ready to burst forth at any moment.”[27] “This earth, although covered all round with a solid crust, is all on fire within. Its interior is supposed to be a burning mass of melted, glowing metals, fiery gas, and boiling lava. * * * * * The solid crust which covers this inward fire is supposed not to be much more than from 9 to 12 miles in thickness. Whenever this crust breaks open, or is cleft in any place, there rush out lava, fire, melted rocks, fiery gases, and ashes, sometimes in such floods as to bury whole cities. From time to time we read of the earth quaking, trembling, and sometimes opening, and of mountains and small islands (which are mountains in the sea) being thrown up in a day.”[28] [27] “The World’s Birthday,” by Professor Gaussen, Geneva, p. 43. [28] “The World’s Birthday,” by Professor Gaussen, Geneva, p. 42. In a periodical called “Recreative Science,” at the end of an interesting article on volcanoes, &c., the following sentence occurs:--“The conclusion is therefore inevitable, that the general distribution all over the earth of volcanic vents, their similarity of action and products, their enormous power and seeming inexhaustibility, their extensiveness of action in their respective sites, the continuance of their energies during countless years, and the incessant burning day and night, from year to year, of such craters as Stromboli; and lastly, the apparent inefficiency of external circumstances in controlling their operations, eruptions happening beneath the sea as beneath the land, in the frigid as in the torrid zone, for these and many less striking phenomena, we must seek for some great and general cause, such only as the central heat of the earth affords us.”