ON January 7 two earthquake tremors were distinctly felt in the district immediately to the east of Mons, one at about 4.30 p.m. and the other at about 8.30 p.m. These were recorded at the Uccle Observatory at 4.29 p.m. and 8.32 p.m. respectively and the epicentre appears to have been near latitude 50° 26′ N., longitude 4° 0′ E. No damage or casualties are reported. It will be remembered that a much stronger earthquake did damage to property and caused injury to ten people in Belgium on June 11, 1938 (NATURE, 144, 950; 1939). On that occasion the epicentre was determined by the chief of the Belgian Seismological Service, Dr. O. Somville, to have been between Audenarde and Renaix, latitude 50° 47′ N., longitude 3° 35′ E. The 1940 epicentre thus appears to have been a little to the south and east of the 1938 epicentre, though any connexion between them is doubtful. The 1938 earthquake had a depth of focus of 45 km. though the 1940 one may have been superficial.