Decades: 1190s 1200s 1210s 1220s 1230s - 1240s - 1250s 1260s 1270s 1280s 1290s
Years: 1237 1238 1239 1240 1241 - 1242 - 1243 1244 1245 1246 1247
Births
Deaths
... gyro tops will not simply fall over, but start precessing around. (The precessing motion is perpendicular to the torque trying to make the gyro fall over.) The axis of ...