"There has been more or less theorizing as to volcanic disturbances moving in cycles, but it cannot be proved. One fact is established, and that is that a volcano is an explosion caused by water coming in contact with the molten mass below the surface of the earth. This is proved by the great clouds of steam that accompany the action. "The old theory that the very center of the earth is a molten mass," he says, "is no longer held." He asserts the latest idea is that the center of the earth is more rigid than glass, though less rigid than steel. About this there is more or less molten matter, and over all the surface crust of the earth. This molten matter causes the surface of the earth to give, to sag, and form what is called "wrinkling." When water comes in contact with the heated mass an explosion follows that finds its outlet through the places where there is least resistance, and the result is a volcano. "There is no part of the earth's surface which is exempt from earthquakes," said Professor Crook, "and there is no regularity in their appearance. Volcanic eruptions are almost always preceded by earthquakes somewhere in the circle. Recently there were earthquakes in the City of Mexico in which many lives were lost. As it is impossible to predict when the next will take place, it is also impossible to tell where it will be. It will certainly be somewhere in the line of the two circles. "All this is of interest as showing that the earth is still in process of formation just as much as it was a billion years ago. We see the same thing in Yellowstone Park. There most decided changes have taken place even in the last eight years. Old Faithful, which used to play regularly every sixty minutes, now does so only once in twice the time." With reference to contributions to science, which might be expected from investigations at Martinique, Professor Crook said: "Even new elements might be discovered, and seismic theories either confirmed or disproved. A volcano always throws off a great variety of materials, hydrochloric and sulphuric acids, iron, silica (sand), sulphur, calcium and magnesium. The lava is of two kinds. That which is easily fusible flows more rapidly than a horse can trot. A more viscous kind cools into shapes like ropes. The latter is common in Hawaii. "The danger of living in proximity to a volcano is usually well known, but the iron oxides render the soil extremely fertile. This is seen in Sicily about AEtna and Vesuvius. It is seen also in Martinique, where an area of forty miles square was occupied by 160,000 people.