Timeline for What were the applications of conic sections before Kepler?
Current License: CC BY-SA 4.0
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| May 3, 2023 at 3:21 | history | edited | Conifold | CC BY-SA 4.0 |
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| Nov 30, 2019 at 2:02 | history | edited | Conifold | CC BY-SA 4.0 |
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| Nov 29, 2019 at 17:32 | vote | accept | Chaim | ||
| Nov 27, 2019 at 22:30 | comment | added | Conifold | @Chaim According to Eusebius, Anaximander "was the first to construct gnomons for the identification of solstices, time spans, horai and the equinox", see Anaximander's Spartan Sundial for a reconstruction. There is no evidence of sundials tracking hours at the time, so he only used it to detect solstices, etc., presumably. There are images of sundials in the linked paper with hyperbola looking cuts, pp. 167,172. | |
| Nov 27, 2019 at 15:00 | comment | added | Chaim | Then the quoted author talks about conical sun-dials. I think we're imagining a cone pointing north, in the attitude of a megaphone in use to shout at someone to the south, and then cut with a plane parallel to the ground to create a sort of bowl. I did a Google image search for "Greek sun-dial" and found some bowl-like examples, but these all looked hemispherical to me rather than conical. How were these shapes helpful? | |
| Nov 27, 2019 at 15:00 | comment | added | Chaim | In the section on sun-dials, the quotation regards something as "quite obvious" that is not really obvious to me. I think that the author is saying that if we trace the path of the shadow across the planar face of a sun-dial on any given day, the trace will be a curve which is one of the conic sections; and the Greeks actually chose "some special days in the year" for this distinction, perhaps meaning a solstice or equinox. | |
| Nov 27, 2019 at 9:45 | history | answered | Conifold | CC BY-SA 4.0 |