The opening of the Taff Vale railway in 1840 and of the South Wales railway to Cardiff in 1850 necessitated further accommodation, and the trustees of the marquess (who died in 1848) began in 1851 and opened in 1855 the East Bute dock and basin measuring 464 acres.
Moreover, Sparta's attention was at this time fully occupied by troubles nearer home - the plots of Pausanias not only with the Persian king but with the Laconian helots; the revolt of Tegea (c. 473-71), rendered all the more formidable by the participation of Argos; the earthquake which in 464 devastated Sparta; and the rising of the Messenian helots, which immediately followed.
His coolness and presence of mind are said to have saved the Spartan state from destruction on the occasion of the great earthquake of 464 (Diodorus xi.
Its length (outside measurement) is 464 ft., its breadth 159 ft.; the nave is 136 ft.
Yet except at the beginning of the 4th century the perioeci were, so far as we can judge, fairly contented, and only two of their cities joined the insurgent helots in 464 B.C. (Thuc. i.
P. 633) emphasizes the former aspect, but there can be little doubt that, at all events after the revolt of 464 (see Cimon), its more sinister purpose was predominant, as we may gather from the secret massacre of 2000 helots who, on the invitation of the ephors, claimed to have rendered distinguished service (Thuc. iv.