Decades: 1120s 1130s 1140s 1150s 1160s - 1170s - 1180s 1190s 1200s 1210s 1220s
Years: 1169 1170 1171 1172 1173 - 1174 - 1175 1176 1177 1178 1179
Births
Deaths
... While the axis is slipping around inside the groove, the friction between the axis and the groove rims will accelerate or brake the spinning gyroscope, with a maximum ...