The following are the particulars of an earthquake felt in the Azores on the night of April 16, 1852; distinguishing the islands from which information has been obtained. St. Mary's; 0°32′ East of the point of observation at St. Michael's. Communicated by Major Guerra, a highly intelligent officer of the Portuguese army, resident at St. Mary's, to his correspondent here. Point of Observation. —The chief town of Villa do Porto, situated on the south-west coast, about 200 feet above the level of the sea, and separated from it by a slightly ascending plain, nearly three miles wide, and W.S.W. (true) of the base of the central ridge, of which the principal peak, Pico Alto*, is 1880 feet in height above the sea. Time and Phenomena. —At a little more than five minutes after ten (10h 8m at St. Michael's?), a slight subterraneous rumbling was followed by a sufficiently perceptible oscillation from south to north, ending in a strong shock, and lasting not less than three seconds. Effects. —No damage appears to have been done to houses and public buildings. St. Michael's; Point of Observation 25° 41′ West of Greenwich. Point of Observation. —The chief town of Ponta Delgada, close to the sea, at an elevation of 70 feet, on an ascent which in about three miles reaches to the top of the central ridge of the island, which in this part rises into peaks of between 1000 and 1600 feet above the sea. Time and Phenomena. —A distinct but not loud rumbling was heard by some persons for about three seconds, and after a perceptible interval, a slight oscillation was