Decades: 790s 800s 810s 820s 830s - 840s - 850s 860s 870s 880s 890s
Years: 838 839 840 841 842 - 843 - 844 845 846 847 848
Births
Deaths
... axis and the groove rims will accelerate or brake the spinning gyroscope, with a maximum effect when the axis starts "rolling" inside the groove. (Compare with graphic ...