All over Italy, from Ischia and Catania in the south to Pavia in the north, the different instruments employed began, one after the other, to write their records of the movement as the unfelt earth-waves sped outwards from the centre. Italy passed, the tale was taken up by magnetographs at Potsdam and Wilhelmshaven, Pawlovsk (near St. Petersburg), Copenhagen, Utrecht, and Parc St. Maur (near Paris); by horizontal pendulums at Strassburg and Shide (in the Isle of Wight), and by a bifilar pendulum at Edinburgh. Shide is 4,891 miles from the centre of disturbance, but, as we shall see, the movement could be traced for a distance greater even than this. [Illustration: FIG. 71.--Seismographic Record of Indian Earthquake at Rocca di Papa. (_Cancani._)] In the more complete records, and especially in those given by the Italian apparatus, Mr. Oldham distinguishes three phases of motion. The first consists of rapid and nearly horizontal movements of the ground. In Italy, it begins at about 11.17 A.M.--that is, about 12-1/2 minutes after the commencement of the shock at the epicentre (Fig. 71, _a_). Without any break in the movement, and after a further interval of about 8-1/2 minutes, the second phase begins; the vibrations are similar to the preceding, but they are larger and more open, and are accompanied by an unmistakable tilting of the surface of the ground (Fig. 71, _b_). Lastly, after the lapse of about twenty minutes more, the second phase gives place, without interruption, to the third (Fig. 71, _c_),[72] consisting of well-marked slow undulations, which have been aptly compared by Professor Milne to the movements caused by an ocean-swell. As they travelled across Europe, the surface of the ground was thrown into a series of flat waves, 34 miles in length, and 20 inches in maximum height, the complete period of each wave being 22 seconds. This phase is by far the longest of the three; in the more sensitive instruments, two or three hours elapsed before their traces ceased to show any sign of movement. [Illustration: FIG. 72.--Seismographic Record of Indian Earthquake at Edinburgh. (_Heath._)] Knowing the distances of the different observatories from the epicentre, and the times taken by each phase to reach them, we can form some idea of the rates at which they travelled. If the early tremors moved in straight lines, their mean velocity for the first phase was 9.0, and for the second 5.3, kilometres per second; but, if they moved along curved paths through the body of the earth, their mean velocities must have exceeded these amounts. For the first undulations of the third phase, the velocity would be 2.9 kilometres per second if they travelled along straight lines, and 3.0 kilometres per second if they were confined to the surface of the earth.