when they are very sudden and very violent that the general public hears of them as the earthquakes which destroy houses, devastate forests, or engulf whole villages."
"Well," said Mr. Curtis, triumphantly, "it seems to me that these facts support what I have just said. Whether the earthquake be great or slight, it must be produced by the same causes; and since these earthquakes occur continually in all parts of the world, it must be because the interior of the earth is in a liquid state."
"Excuse me," said Dr. Giles; "but I was about to add that the subject of earthquakes has been very carefully studied by seismologists, and the best authorities have calculated that the origin of the disturbance is usually not very deep in the interior of the earth—probably not over thirty miles below the surface in the most violent earthquakes, and certainly at a much slighter depth than this in many cases. Now, if the whole interior of the earth were in a liquid state, it would be natural to expect that the origin of our earthquakes would be at a much greater depth."
"So far as you are concerned," remarked Mr. Curtis, "I don't see that it makes very much difference whether the whole interior of the earth
