Decades: 820s 830s 840s 850s 860s - 870s - 880s 890s 900s 910s 920s
Years: 867 868 869 870 871 - 872 - 873 874 875 876 877
Births
Deaths
... device will cause the gyroscope to start precessing, with its axis slipping around in the groove in a circular fashion. The groove inside the device, is a little wider ...