"सेकेंड": अवतरणों में अंतर

The day was subdivided [[sexagesimal]]ly, that is by {{frac|1|60}}, by {{frac|1|60}} of that, by {{frac|1|60}} of that, etc., to at least six places after the sexagesimal point by the [[Babylonia]]ns after 300 BC, but they did not sexagesimally subdivide smaller units of time. For example, six fractional sexagesimal places of a day was used in their specification of the length of the year, although they were unable to measure such a small fraction of a day in real time. As another example, they specified that the mean synodic month was 29;31,50,8,20 days (four fractional sexagesimal positions), which was repeated by Hipparchus and Ptolemy sexagesimally, and is currently the mean synodic month of the [[Hebrew calendar]], though restated as 29 days 12 hours 793 [[helek|halakim]] (where 1 hour = 1080 halakim).<ref>Otto Neugebauer, ''A history of ancient mathematical astronomy'' (Berlin: Springerस्प्रिंगर, 1975)</ref> They did not use the hour, but did use a double-hour, a time-degree lasting four of our minutes, and a barleycorn lasting 3⅓ of our seconds (the ''helek'' of the modern Hebrew calendar).<ref>Otto Neugebauer, "The astronomy of Maimonides and its sources", ''Hebrew Union College Annual'' '''22''' (1949) 321-60, p. 325.</ref>