DURING May ten strong earthquakes Were registered at observatories throughout the world, and there were numerous smaller shocks and tremors. The greatest earthquake which was registered at Kew gave ground amplitudes of 110 µ at Kew on May 14 and came from a focus the epicentre of which was south of the Alaska Peninsula (lat. 54½° N., long. 161° W.). A World-shaking aftershock of this came on May 17 from a focus the epicentre of which was perhaps slightly to the north of the original. The second most intense shock of the month was the one which occurred on May 11, starting from a focus with epicentre near lat. 17° S., long 71° W. in southern Peru. The focus of this earthquake was a little deeper than normal ; the instrumental strength of the shock Was almost 7½, and casualties and damage were caused at Moquegua in southern Peru and at Arica and Tacua in northern Chile. The third greatest earthquake shock of the month happened on May 25 from a focus having an epicentre near lat 30° N., long. 99½ E. in Sikang Province in China. A much less intense earthquake on May 28 from a focus with epicentre at lat. 12° S., long. 77° W. did damage to property and caused the deaths of five people in Peru. The deepast focus earthquake of the month occurred on May 23 from a focus some 200 km. deep with epicentre near lat. 18° S., long. 169° E. More feeble shocks occurred on May 23, doing damage to property in both islands of New Zealand ; on the morning of May 24, throwing people out of bed at Palermo in Sicily ; and on May 25, off the west coast of Oregon. Data for the month have been received from the U.S. Coast and Geodetic Survey, the International Seismological Bureau at Strasbourg, and observatories at Beograd, De Bilt, Durham, Kew, Stuttgart, Toledo and Uccle.