Arabic Temporal Watch

What it is

A watch with two dials on one face. The inner dial is an ordinary twelve-hour clock. The outer ring carries the twenty-four named Arabic hours — الفجر, الصبح, الصباح, through to السحر, the hour before dawn — and turns so that the hour currently running sits under the hour hand.

The two stay locked together because the geometry makes them: twenty-four slots at thirty degrees each is two full turns, and the hour hand also turns twice a day. Civil time and temporal time are therefore read in one glance rather than converted between.

Why the hours are not equal

The Arabic hours in this system are anchored to prayer times, not to the clock. The day is cut into six spans between consecutive prayers, and each span carries a fixed number of named hours: three between Fajr and sunrise, five between sunrise and Dhuhr, eight between Isha and Fajr, and so on.

What is stored for each hour is a proportion of its span, never a count of minutes. Because the spans lengthen and shorten through the year, so do the hours. The same named hour is genuinely longer in winter than in summer, which is the property that makes the system temporal rather than decorative. The proportions within each span always sum to one, and can be adjusted.

The thirds of the night

The night runs from Maghrib to the following Fajr and is divided into three equal parts, recomputed each day from that day's actual times. They are not fixed three-hour blocks.

• Night measured across midnight

  Both ends are full timestamps rather than clock times. Subtracting 03:00 from 18:00 as same-day numbers yields a negative night, and correcting that with a modulo produces a plausible, wrong answer.

• Fajr taken from the correct date

  Three days of timings are loaded, so the night in progress is bounded by one day's Maghrib and the next day's Fajr. Reusing today's Fajr for tomorrow morning would introduce a small daily error.

• Nothing shown outside the night

  Between Fajr and Maghrib no third is current, and none is displayed as if it were. The panel says so and lists the coming night's times instead.

• Adjustable dawn angle

  There is no single astronomical value for dawn that every authority agrees on. The methods offered span 15° to 19.5°, the angle in force is shown, and the choice is a setting.

The watch

This watch needs a location

Dawn and sunset depend on where you are, so nothing is calculated until you say. Nothing is stored on the site — your choice stays in this browser.

Time and place

The dial reads the device clock directly on every frame rather than advancing a counter of its own, so it cannot drift and recovers immediately after the machine sleeps. Prayer times are requested in the visitor's own timezone, which is what makes them comparable to that clock.

Nothing is computed until a location is given, either by permission or by choosing a place. Dawn and sunset are properties of a place, and assuming one silently produces times that look authoritative and are wrong.