ON May 3, shortly before 9.26 a.m., a sharp local earth-shake was felt, chiefly in the coal-mining district to the north-west of Manchester. The area in which the shock was strongly felt is about 13 miles long and 9 or 10 miles wide, and includes about 100 square miles, but at one or two places outside it was also slightly felt. The shock was strong enough to cause slight damage, such as overthrowing chimney-pots, at Eccles, Irlam-o'-th'-Heights, Patricroft, etc. Tremors were recorded at the Stonyhurst College observatory, beginning at 9 h. 25 m. 56 s. and lasting 40 sec., but not at the Godlee observatory in Manchester nor at the Bidston observatory near Birkenhead. The small disturbed area (probably less than 200 square miles) and the high intensity near its centre point to a very slight depth of focus, such, for example, as the depth of the coal-seams worked in the district. The longer axis of the disturbed area runs about north-west and south-east, in the direction of the Pendleton or Irwell Valley fault, and the centre of the area lies close to the fault-line. It is probable that the earth-shake was caused by a slip along this fault, and that the slip was precipitated, not by natural causes, as in the Bolton earthquake of Feb. 10, 1889, but by the removal of coal in the neighbourhood of the fault. It is of some interest to notice that the disturbed area of the recent earth-shake almost coincides with that of one, not quite so strong, that occurred on Nov. 25, 1905, and that the places where slight damage to chimneys occurred last Sunday lie close to the centre of the innermost isoseismal of 1905, and to the centres of similar but still slighter shocks on Feb. 27, 1899, and April 7, 1900 (Geol. Mag., vol. 7, p. 175; 1900: vol. 8, p. 361; 1901: and vol. 3, pp. 171-176; 1906).