Sundial Ring and Nocturnal: Does Anyone Have the Time?
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- Опубликовано: 21 июл 2024
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Before the advent of accurate mechanical clocks, people used a variety of celestial instruments to tell time by the movement of the sun and the stars. In this episode we look at two examples of such instruments: an Aquitaine sundial ring - a replica of a device supposedly given by Eleanor of Aquitaine to King henry II in 1152 - and a nocturnal, a device developed in the 16th Century for measuring time at night.
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FURTHER READING:
sundials.org/index.php/teache...
www.shadowspro.com/en/sundial...
plus.maths.org/content/analem...
www.mysundial.ca
A legend I was told (and this may be utter nonsense but it sounds good) was that if you arrived while the shadow of the gnomon was still in the nick carved in the face of a stone dial, you had arrived “in the nick of time”.
The gods confound the man who first found out how to distinguish hours!
Confound him too, who in this place set up a sundial
to cut and hack my days so wretchedly into small portions!
When I was a boy, my belly was my sundial: one more sure,
truer, and more exact than any of them.
This dial told me when it was time to go to dinner, when I had
anything to eat; but nowadays, why even when I have, I can’t fall-to
unless the sun gives leave.
The town’s so full of these confounded dials, the greatest part of
its inhabitants, shrunk up with hunger, creep along the streets.
-- Roman comic playwright Plautus.
Fascinating, I like the short ones mixed in with the longer videos. Great work.
This channel deserves more views. Well presented and interesting.
Great video, Gilles...👍
Very nice
cool. thx.
A nocturn if properly made van be within 20 min in practical use. And that ring about 30 min or so. Time with better precision require a sextant lunar sight, that xan place you within minute in time with practice
Where did you find your nocturnal clock? I'd love to add one to my collection of watches/clocks/timekeepers! Thanks!
Lee Valley Tools. Though I don't think they carry it anymore :(
@@CanadianMacGyver>>> They do not carry them anymore? 😞
I was also looking for a nocturnal like the one in ur vid😂, Shame I can’t find anything equivalent in size and design lol
Is that a gnomon in your pocket or are you just looking for a good time?
1:38 “Time is measured by the azimuth of the Sun”: You are showing a standard garden sundial with an inclined gnomon. This measures BOTH altitude and azimuth, so it tends to be more accurate. The sundial that measures only the azimuth is an ANALEMMATIC sundial, which is a fairly late invention due to the complex trigonometry involved.
You state that sundials were used to tell time before the invention of clocks. That is true, but the standard garden sundial is an equal-hour dial, that was invented so that it would read the same as mechanical clock. Mechanical clocks were owned only by wealthy people. Since wealthy people set the rules and decreed what time it was, everyone else was forced to follow suit.
In other words, what everyone pictures as a sundial is actually more modern than the mechanical clock. Also note that until the invention of the telegraph allowed clocks to be synchronized over wide areas, if you lived in the boondocks and ordered a clock, it came with a small sundial that you would set in your window sill so you could set the clock, as there was no WWV or other time-signal. (Aside from cannons being fired at noon in port cities.)
The Aquitaine sundial is in the general class of Perforated-Ring Dials. After having tinkered with the design of Perforated-Ring Dials over the past 25 years, I have designed one that is calibrated for a particular latitude and longitude and time of year, is accurate to five minutes, is about three inches in diameter (so can be worn as a bracelet) and (Ta Da!) reads wall-clock time directly as the equation of time and local time zone corrections (and DST) have already been applied.
I also built a vertical wall dial that was originally accurate to 90 seconds, but it has become warped and has lost accuracy. The British have built the most accurate dial, accurate to 40 seconds. It’s made of surgical steel and looks like a prop from Star Trek.
Fred,
Thanks for the information! Sundials are not my speciality by any measure, so I thought it best to speak in very general terms for the sake of clarity. The idea in the first case was simply to contrast the ring-dial with the kind of sundial most people would be familiar with. In the case of calibrating clocks with sundials and vice-versa, you could of course determine local noon independently using a sextant or dipleidoscope, but most people don't own either of those instruments and so would have to use a modern clock anyway.
Is the British one you mention the one in the royal.. garden? Park? Near Buckingham palace? Where a bunch of exotic birds live? I seem to recall that has _a_ quite minimalist-looking sundial.
@@kaitlyn__L Now that you mention it, I don’t know. I just assumed it was at Greenwich ’cause that’s where ALL the cool timekeeping stuff is.
Good video, sometimes less is more.