that there is a central fire in the interior of the earth?"
"It proves that there are certain incandescent masses in the interior, but not that the whole center of the earth is in a molten condition. In fact, if the earth were liquid at the center, the incandescent matter, or sea of fire, would have tides just as our oceans of water have. Consequently every active volcano would have each day two high and two low tides, whereas nothing of the sort happens. Indeed, all the manifestations with which we are familiar accord more closely with the theory of a solid earth than of one containing a sea of molten matter."
"But how about earthquakes? Do not earthquakes occur continually in every portion of the globe? And are not these earthquakes caused by internal heat?"
"True; but the earthquakes only lend support to what I have said. It is an undeniable fact that the land in almost every country on the face of the earth is slowly but continually either rising or falling. These elevations and depressions are, however, so gradual that most persons do not even notice them; in fact, very delicate instruments are required to ascertain their occurrence. It is only
