_Seismic Sea-Waves._--Immediately after the earthquake, the sea retired a short distance, variously estimated at from ten to thirty metres, laying bare some rocks that were usually immersed. At P. Maurizio, the surface was lowered by a little more than a metre; and after a few minutes it rose to nearly a metre above its original level, returning to it after a series of continually-decreasing oscillations. At San Remo, a fall of about the same amount took place, the sea returning after five minutes, and a ship anchored in the harbour broke from her moorings. Again, at Antibes, the sea was suddenly lowered by about a metre, so that ships afloat in the harbour were aground for some instants, and then returned with some impetuosity to its original level. [Illustration: FIG. 38.--Record of tide-gauge at Nice. (_Issel._)] The evidence of eye-witnesses is confirmed by that of the tide-gauges at Nice and Genoa, the curves of which are reproduced in Figs. 38 and 39. At Nice, the first arrest of the curve in its usual course occurred at 6.30 A.M.;[52] the sea-level sank somewhat abruptly, and after a few marked oscillations gradually returned to its normal position at 7.50 A.M. At Genoa, the shock caused the writing-pen of the tide-gauge to dent the paper on which the record is made, and soon afterwards the curve shows a series of irregular oscillations, about eight taking place every hour, and gradually decreasing until they ceased to be perceptible about two hours after the principal earthquake. [Illustration: FIG. 39.--Record of tide-gauge at Genoa. (_Issel._)] MISCELLANEOUS PHENOMENA. _Connection between Geological Structure and the Intensity of the Shock._--As with the Andalusian earthquake, faulty construction and defective materials were responsible for much of the damage caused by the Riviera earthquake. But, if we may judge from the sharp local variations in its amount, the nature of the surface-rocks must have exerted a still more potent influence. At Cervo, for example, the injury to property amounted to less than £3 per head of the population; at Diano Marina, only two or three miles to the west, it rose to £22 per head. The death-rate at Cervo was about one-tenth, and at Diano Marina about 8-1/2 per cent. Again, at Mentone, the damage must have been considerable, for about 155 houses were rendered uninhabitable; while Monte Carlo, only a few miles farther west, escaped almost unharmed. Now, Mentone and Diano Marina are for the most part built on clay or alluvial deposits, and Monte Carlo on a foundation of limestone.