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mcal: update metadata, navbar, and add basic explanation

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mcal/index.html
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8"/>
<link rel="icon" href="%PUBLIC_URL%/favicon.ico"/>
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<meta name="theme-color" content="#ff0000"/>
<meta name="description" content="An interactive French Republican Calendar (a.k.a. French Revolutionary Calendar) that uses the original equinox method and never drifts out of sync with the seasons, along with revolutionary decimal time."/>
<meta property="og:title" content="French Republican Calendar"/>
<meta property="og:type" content="website"/>
<meta property="og:url" content="%PUBLIC_URL%"/>
<meta property="og:description" content="An interactive French Republican Calendar (a.k.a. French Revolutionary Calendar) that uses the original equinox method and never drifts out of sync with the seasons, along with revolutionary decimal time."/>
<meta property="og:image" content="%PUBLIC_URL%/logo512.png"/>
<meta property="og:image:type" content="image/png"/>
<meta property="og:image:width" content="512"/>
<meta property="og:image:height" content="512"/>
<meta property="og:image:alt" content="A calendar icon that displays the date 18 Brumaire."/>
<link rel="canonical" href="%PUBLIC_URL%/"/>
<link rel="apple-touch-icon" href="%PUBLIC_URL%/logo192.png"/>
<link rel="manifest" href="%PUBLIC_URL%/manifest.json"/>
<title>French Republican Calendar (a.k.a. French Revolutionary Calendar)</title>
</head>
<body>
<nav class="navbar navbar-expand-md navbar-light">
<div class="container">
<a class="navbar-brand" href="#">French Republican Calendar</a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#nav-anchors"
aria-controls="nav-anchors" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="nav-anchors">
<ul class="nav navbar-nav mr-auto">
<li class="nav-item">
<a class="nav-link" href="#explanation">Explanation</a>
</li>
<li class="nav-item">
<a class="nav-link" href="https://jcal.qt.ax">Julian Calendar</a>
</li>
<li class="nav-item">
<a class="nav-link" href="https://gcal.qt.ax">Gregorian Calendar</a>
</li>
</ul>
</div>
</div>
</nav>
<noscript>You need to enable JavaScript to run this app.</noscript>
<div id="root"></div>
<div class="main">
<h2 id="explanation">Explanation</h2>
<div class="card">
<div class="card-body">
<h4 class="card-title">What is this?</h4>
<p class="lead">The <a href="https://en.wikipedia.org/wiki/French_Republican_calendar">French Republican
calendar</a> was a calendar created and implemented during the French Revolution.</p>
<p>It is also frequently referred to as the <em>French Revolutionary Calendar</em>, but this is a misnomer:
year 1 of the calendar started on 22 September 1792, the day after the
<a href="https://en.wikipedia.org/wiki/Proclamation_of_the_abolition_of_the_monarchy">abolition of the
monarchy</a> and the founding of the <a href="https://en.wikipedia.org/wiki/French_First_Republic">French
First Republic</a>.</p>
</div>
</div>
<div class="card">
<div class="card-body">
<h4 class="card-title">How does it work?</h4>
<p class="lead">A year consists of 12 months of 30 days each, divided into three <em>décades</em> of 10 days
each, followed by 5 complementary days (6 in leap years).</p>
<p>The year starts on the day of the autumnal equinox at the Paris Observatory (longitude 2°20′14.03″ E). A
leap year follow directly from this definition: a year is a leap year when the next autumnal equinox
happens 366 days later instead of the normal 365. By this definition, the year will <b>never</b> drift
with respect to the seasons.</p>
<p>The 12 months are: <em>Vendémiaire</em>, <em>Brumaire</em>, <em>Frimaire</em>, <em>Nivôse</em>, <em>Pluviôse</em>,
<em>Ventôse</em>, <em>Germinal</em>, <em>Floréal</em>, <em>Prairial</em>, <em>Messidor</em>, <em>Thermidor</em>,
<em>Fructidor.</em> Every three months represent a season, and the endings of the names reflect this
fact.</p>
<p>The complementary days are: <em>la Fête de la Vertu</em>, <em>la Fête du Génie</em>, <em>la Fête du
Travail</em>, <em>la Fête de l'Opinion</em>, <em>la Fête des Récompenses,</em> and <em>la Fête de la
Révolution</em> (leap years only).</p>
</div>
</div>
<div class="card">
<div class="card-body">
<h4 class="card-title">What's so special about this version?</h4>
<p class="lead">Most versions of the calendar floating around doesn't use the original definition above.</p>
<p>Most versions uses the so-called <em>Romme</em> method for leap years, using the same leap year rules as
the Gregorian calendar, i.e. every year divisible by four, except century years not divisible by 400.
This method might make sense, except years 3, 7, and 11 were leap years under the original rules and
were observed as such in real life, but the <em>Romme</em> method instead makes years 4, 8, 12 leap
years instead.</p>
<p>This version uses the original rules. The <a href="https://ssd.jpl.nasa.gov/planets/eph_export.html">JPL's
DE440 and DE441 ephemerides</a> were used to calculate the exact timings of the autumnal equinoxes
between the Gregorian years 13201 BCE and 17191 CE (corresponding to the French Republican years -14991
to 15399). The times were then converted to UT1+00:09:21, the exact local time at the Paris Observatory.
UT1 was chosen to keep track of the Earth's rotation without having to worry about the issues posed by
leap seconds in UTC. Note that due to the uncertainty over
<a href="https://en.wikipedia.org/wiki/%CE%94T_(timekeeping)">ΔT</a> — the difference between UT1 and
Terrestrial Time (TT) used in the ephemerides — it is theoretically possible for there to be
inaccuracies when the equinox occurs very close to midnight.</p>
<p>For more details about how I calculated this calendar, please see
<a href="https://quantum5.ca/2022/03/09/art-of-time-keeping-part-4-french-republican-calendar/">my blog
post on the topic</a>. This is the fourth part of a series on time-keeping, and you are highly
encouraged to read the
<a href="https://quantum5.ca/2022/02/16/art-of-time-keeping-part-1-years-dates/">first</a>
<a href="https://quantum5.ca/2022/02/23/art-of-time-keeping-part-2-time/">three</a>
<a href="https://quantum5.ca/2022/03/02/art-of-time-keeping-part-3-astronomy-equinoxes/">parts</a>
for a more complete understanding.</p>
</div>
</div>
<div class="card">
<div class="card-body">
<h4 class="card-title">What are those names above the Gregorian date?</h4>
<p>Those are the names of the days in the
<a href="https://en.wikipedia.org/wiki/French_Republican_calendar#Rural_calendar">rural version of the
calendar</a>. This was intended to replace the Catholic Church's calendar of saints, as the French
Revolution wanted to reduce the influence of the church. Every day of the year has a unique name
associated with the rural economy and these names are supposed to correspond with the season.</p>
<p>Every <em>quintidi</em> is named after an animal, every <em>décadi</em> is named after an agricultural
tool, and the remaining days are named after various plants or produce. The only exception is the winter
month of Nivôse, which has the remaining days named after minerals.</p>
</div>
</div>
<div class="card">
<div class="card-body">
<h4 class="card-title">What are those numbers below the Gregorian date?</h4>
<p>The five (or more) numbers separated by dots is the corresponding
<a href="https://en.wikipedia.org/wiki/Mesoamerican_Long_Count_calendar">Mesoamerican Long Count
calendar</a> date. This is commonly known as the &ldquo;Mayan calendar.&rdquo; This calendar is not
available for dates before August 11, 3114 BCE (25 Thermidor -4905).</p>
</div>
</div>
<div class="card">
<div class="card-body">
<h4 class="card-title">What is decimal time?</h4>
<p class="lead">Decimal time is a time system used during the French Revolution that divided the day into 10
hours, each with 100 minutes, which contained 100 seconds each.</p>
<p>The result is 100,000 seconds in one day, compared to the 86,400 seconds with the normal 24-hour
system. This makes it very easy to denote time as a decimal fraction of a day. For example, decimal time
5:67:72 (around 13:37:31) on January 1, 2000 can be represented as <code>2000-01-01.56772</code>.</p>
<p>Also note that each decimal hour is 2.4 normal hours, each decimal minute is 1.44 normal minutes, and
each decimal second is 0.864 normal seconds.</p>
</div>
</div>
</div>
<footer class="footer">
<div class="container">
<p class="text-muted">Copyright &copy; 2022-<%= new Date().getFullYear() %>
<a href="https://quantum5.ca">Quantum</a>.
Licensed under <a href="https://www.gnu.org/licenses/agpl-3.0.en.html">GNU AGPLv3</a>.
Source code available on <a href="https://github.com/quantum5/qcal">GitHub</a>.<br>
</p>
</div>
</footer>
<script>
(function(r,e,p,u,b,l,i,c){r['GoogleAnalyticsObject']=b;r[b]=r[b]||function(){
(r[b].q=r[b].q||[]).push(arguments)},r[b].l=1*new Date();l=e.createElement(p),
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ga('create', 'UA-102581070-4', 'auto');
ga('send', 'pageview');
</script>
</body>
</html>

65
mcal/public/index.html
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@ -5,25 +5,27 @@
<link rel="icon" href="%PUBLIC_URL%/favicon.ico"/>
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<meta name="theme-color" content="#ff0000"/>
<meta name="description" content="An interactive French Republican Calendar (a.k.a. French Revolutionary Calendar) that uses the original equinox method and never drifts out of sync with the seasons, along with revolutionary decimal time."/>
<meta property="og:title" content="French Republican Calendar"/>
<meta name="description"
content="An attempt to present the Mayan calendar system in a more familiar calendar format."/>
<meta property="og:title" content="Mayan Calendar"/>
<meta property="og:type" content="website"/>
<meta property="og:url" content="%PUBLIC_URL%"/>
<meta property="og:description" content="An interactive French Republican Calendar (a.k.a. French Revolutionary Calendar) that uses the original equinox method and never drifts out of sync with the seasons, along with revolutionary decimal time."/>
<meta property="og:description"
content="An attempt to present the Mayan calendar system in a more familiar calendar format."/>
<meta property="og:image" content="%PUBLIC_URL%/logo512.png"/>
<meta property="og:image:type" content="image/png"/>
<meta property="og:image:width" content="512"/>
<meta property="og:image:height" content="512"/>
<meta property="og:image:alt" content="A calendar icon that displays the date 18 Brumaire."/>
<meta property="og:image:alt" content="A calendar icon that displays the Mayan date of creation."/>
<link rel="canonical" href="%PUBLIC_URL%/"/>
<link rel="apple-touch-icon" href="%PUBLIC_URL%/logo192.png"/>
<link rel="manifest" href="%PUBLIC_URL%/manifest.json"/>
<title>French Republican Calendar (a.k.a. French Revolutionary Calendar)</title>
<title>Mayan Calendar</title>
</head>
<body>
<nav class="navbar navbar-expand-md navbar-light">
<div class="container">
<a class="navbar-brand" href="#">French Republican Calendar</a>
<a class="navbar-brand" href="#">Mayan Calendar</a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#nav-anchors"
aria-controls="nav-anchors" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
@ -34,6 +36,9 @@
<li class="nav-item">
<a class="nav-link" href="#explanation">Explanation</a>
</li>
<li class="nav-item">
<a class="nav-link" href="https://frcal.qt.ax">French Republican Calendar</a>
</li>
<li class="nav-item">
<a class="nav-link" href="https://jcal.qt.ax">Julian Calendar</a>
</li>
@ -51,13 +56,32 @@
<div class="card">
<div class="card-body">
<h4 class="card-title">What is this?</h4>
<p class="lead">The <a href="https://en.wikipedia.org/wiki/French_Republican_calendar">French Republican
calendar</a> was a calendar created and implemented during the French Revolution.</p>
<p>It is also frequently referred to as the <em>French Revolutionary Calendar</em>, but this is a misnomer:
year 1 of the calendar started on 22 September 1792, the day after the
<a href="https://en.wikipedia.org/wiki/Proclamation_of_the_abolition_of_the_monarchy">abolition of the
monarchy</a> and the founding of the <a href="https://en.wikipedia.org/wiki/French_First_Republic">French
First Republic</a>.</p>
<p class="lead">This is an attempt to render the <a href="https://en.wikipedia.org/wiki/Maya_calendar">Mayan
calendar</a> in a more familiar &ldquo;monthly&rdquo; calendar format.</p>
<p>The idea of a monthly calendar is sort of alien to the Maya, who used two cycles to track the date and
a modified base-20 numbering system to track the exact date:</p>
<ul>
<li>The <a href="https://en.wikipedia.org/wiki/Tzolk%CA%BCin"><strong>tzolkʼin</strong></a>
cycle, which is a 260-day cycle based on combining 20 day names with 13 numbers, used for religious
and ceremonial events and for divination;
</li>
<li>The <a href="https://en.wikipedia.org/wiki/Haab%CA%BC"><strong>haabʼ</strong></a> cycle, which is a
365-day cycle consisting of 18 &ldquo;months&rdquo; of 20 day each, plus 5 days at the end of the
year known as the <em>Wayebʼ</em>;
</li>
<li>The <a href="https://en.wikipedia.org/wiki/Mesoamerican_Long_Count_calendar"><strong>Long
Count</strong></a>, a modified base-20 system used to represent the number of days since the
mythical date of creation, which is August 11, 3114 BCE in the proleptic Gregorian calendar or
September 6, 3114 BCE in the proleptic Julian calendar. It is typically represented as five numbers
separated by dots, with each number counting from 0 up to 19, except for the second last number,
which counts from 0 to 17.
</li>
</ul>
<p>Since the <em>haabʼ</em> is the closest equivalent to months in the Mayan system, this calendar
application is based on the <em>haabʼ</em>. This poses a problem, as in the Mayan system, the Long Count
is used to track the absolute date and the cycles of <em>tzolkʼin</em> and <em>haabʼ</em> are
unnumbered. To mitigate this issue, we attempt to number the <em>haabʼ</em> cycles, with the date of
creation in cycle 0.</p>
</div>
</div>
<div class="card">
@ -151,10 +175,17 @@
</div>
</footer>
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