Chains generally last longer than belts, but they sit in engine oil, so if the engine’s lubrication maintenance is neglected, the chain will suffer along with it and wear out faster. The timing ...

This video was inspired by this paper: B. Goldstein, ‘Ibn Muʿādh’s Treatise on Twilight and the Height of the Atmosphere’, Archive for History of Exact Sciences, vol. 17, no. 2 (1977), pp.