| Index | Recent Threads | Unanswered Threads | Who's Active | Guidelines | Search |
 |
World Community Grid Forums
Category: Community
Forum: Chat Room
Thread: Here's a question - Why do clocks only go up to 12? |
| No member browsing this thread |
|
Thread Status: Active Total posts in this thread: 16
|
|
| Author |
|
|
David Autumns
Ace Cruncher UK Joined: Nov 16, 2004 Post Count: 11062 Status: Offline Project Badges: 
|
So it turned out not to be such a daft question after all
---------------------------------------- Thanks to you all for taking the time (  this is for Dave B) to replyWe've all learnt something today very informative. Thanks Dave  |
||
|
|
Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
Dave --
I did some research on the internet on this topic and, as has been said, the 12 hour cycle has its roots in the lunar cycle. It appears to go all they way back into ancient Egypt where the period between sunset and sunrise was divided into 12 segments. They then also divided the period between sunrise and sunset similarly which resulted in the 24 hours we know today -- well, not quite. Since Egypt is near the equator, days and nights are relatively the same in length. It was not until the medieval period when mechanical clocks came into being that dividing the day and night each into 12 segments became a problem because of seasonal differences in the lengths of days and nights, especially at the northern latitudes found in European centers of civilization. Can you imagine trying to design a clock that would measure the time between sunrise and sunset as 12 "hours" in, for example, London? Using our current clocks, sunrise and sunset are as follows: June 21, 2005: Sunrise 4:43 AM; Sunset 9:21 PM (16 hours 38 munutes) December 21, 2005: Sunrise 8:04 AM; Sunset 3:54 PM (7 hours 54 minutes) It would have taken some very interesting gearworks to divide both into 12 equal segments. -- Dave |
||
|
|
Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
But who set the first clock? And more importantly, how do we know they were right?
Paul |
||
|
|
Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
But who set the first clock? And more importantly, how do we know they were right? I'm with you, UKSCS. In fact, I feel sure that they started that first clock 2 hours early! I was thinking something like that this morning as I rolled muzzily out of bed. I feel vindicated now that I know that someone else is pursuing this line of thought.Paul mycrofth |
||
|
|
retsof
Former Community Advisor USA Joined: Jul 31, 2005 Post Count: 6824 Status: Offline Project Badges:
|
Can you imagine trying to design a clock that would measure the time between sunrise and sunset as 12 "hours" in, for example, London? We're actually back to that....Islamic prayer clocks...which are interested in the time of local sunrise and sunset for 5 prayers daily, current location so they can find the direction of Mecca, and visibility of the new moon to start off a new month. Here's a quote about the features of one: Finally a solution to our busy lifestyle has arrived. This 5 Times fully automatic azan has taken the pain out of setting and re-setting the prayer timings. This clock automatically adjusts to the changes in prayer timings. You don’t have to set timings of every prayer yourself, just set your local time and enter your city code (given in the clock manual) and your clock will set your local prayer timings for all 5 prayers. You even don’t have to worry about re-setting timings for Maghrib after every few days because your clock will do it automatically. You can select between Hijra and Georgian calendars. And adjusting to daylight saving time (DST) is easier then you could ever imagine – just press the DST button and the time as well as all 5 prayer timings will reset automatically. Preset for 101 cities around the world. 1 year guarantee. Here's the result for an online prayer calculator for Austin TX for today: IslamiCity Prayer Times for Austin (Texas), USA Latitude : 30 18 'N' Longitude : 97 42 'W' Time Zone : -6 H Qibla : 43 31 45 E (From N) -------------------------------------------------------------------------------- Thursday September 8, 2005 (4 Sha`ban 1426) 4:26:35 PM (Austin ) Fajr (Dawn) Shorook (Sunrise) Zuhr (Noon) Asr (Afternoon) Maghrib (Sunset) Isha (Night) 5:50 7:12 1:28 5:00 7:45 9:06 A few fancy-dancy watches can calculate Easter. It's the first Sunday after the first first full moon after the vernal equinox. The Naval Observatory mentions that different religions use different tables. http://aa.usno.navy.mil/faq/docs/easter.html Simple. There is a room in the Vatican (Tower of the Winds) with a small hole that lets a beam of sunlight shine on a spot on the floor to monitor this.
SUPPORT ADVISOR
----------------------------------------Work+GPU i7 8700 12threads School i7 4770 8threads Default+GPU Ryzen 7 3700X 16threads Ryzen 7 3800X 16 threads Ryzen 9 3900X 24threads Home i7 3540M 4threads50% [Edit 5 times, last edit by retsof at Sep 8, 2005 9:46:49 PM] |
||
|
|
David Autumns
Ace Cruncher UK Joined: Nov 16, 2004 Post Count: 11062 Status: Offline Project Badges:
|
It turns out that a day is 23 hours 56 minutes and 4.091 seconds long.
----------------------------------------We are being conned out of nearly 4 minutes a day! This increases by 2 milliseconds every 100 years because the earth is slowing down. I don't believe this as I'm sure time speeds up as you get older  This thread is ticking ( ) along nicely |
||
|
|
|