Decades: 1180s 1190s 1200s 1210s 1220s - 1230s - 1240s 1250s 1260s 1270s 1280s
Years: 1229 1230 1231 1232 1233 - 1234 - 1235 1236 1237 1238 1239
Births
Deaths
... action towards the externally applied force will cause one end of the axis to push against the upper rim of the groove, while the other end of the axis pushes agains ...