When a large earthquake occurs in any part of the earth, its tremors can be recorded on suitable instruments all over the surface of the globe. These instruments are of various types, the most familiar being the horizontal pendulum, the evolution of which we owe to the labours of a small band of enthusiasts who were engaged by the Japanese Government in the late seventies and early eighties to teach the students of Japan the scientific methods of the West. The most conspicuous of these is undoubtedly Professor John Milne, who in his seismological laboratory established in the Isle of Wight continues to study the mysterious movements of the earth. Prompted by him, the British Association has installed some fifty instruments in various parts of the world; and from the accumulating records furnished by these instruments, Milne pursues his seismological studies. In addition to these fifty British Association stations, there have grown up in recent years many seismological laboratories in Europe, Asia, and America; and the data supplied from all these sources place us in a much better position than ever before to draw sure conclusions from the character of the records.