This post was written by Peter de Clercq

You only have to walk around in your own town to observe that of all the public clocks you pass by, only a few tell the correct time. Many show just any time, others have stopped working altogether.

Last year, a tongue-in-cheek editorial in the Guardian suggested that it was ‘time for a public clock tsar, with power to demand that owners restore their timepieces to reliable service’.

Here I learned of the existence of the blogspot Stoppedclocks, which invites us to ‘help find and fix all the stopped public clocks in Britain’. So if you have a particular gripe about a faulty clock in your area, you now know where to turn to.

There is, of course, nothing new under the sun. More than three centuries ago a correspondent to a London newspaper ventilated his gripe about the unreliability of public time-pieces.

It is quoted here, with the numbers referring to the map, as published in an article by Anthony Turner entitled ‘From sun and water to weights: public time devices from late Antiquity to the mid-seventeenth century’, published in Antiquarian Horology in March 2014.

'I was in Covent Garden 1 when the clock struck two, when I came to Somerset-house 2 by that it wanted a quarter of two, when I came to St. Clements 3 it was half an hour past two, when I came to St. Dunstans 4 it wanted a quarter of two, by Mr. Knib’s Dyal in Fleet-street 5 it was just two, when I came to Ludgate 6 it was half an hour past one, when I came to Bow Church 7, it wanted a quarter of two, by the Dyal near Stocks Market 8 it was a quarter past two, and when I came to the Royal Exchange 9 it wanted a quarter of two: This I aver for a Truth, and desire to know how long I was walking from Covent Garden to the Royal Exchange ?'

(Quoted from The Athenian Mercury, vi no 4, query 7, 13 February 1692/93).

This post was written by David Thompson

Many thousands of people today have stood amazed in front of the Astronomical Clock in the Old Town Hall Square in Prague, but I wonder just how many have managed to make sense of the dial. In modern times, perhaps it makes little sense.

The clock was made by Jan Šindel in about 1410, and from as early as the 15th century, the clock had a 24 hour dial which showed the so-called Bohemian Hours, a system in which the day began and ended at sunset.

This means, of course, that the 24-hour ring around the outside had to be adjusted periodically so that the 24th hour coincided with sunset.

In the early part of the clock’s life this was done manually, but later an automatic mechanism was installed to adjust the position of the ring. In medieval Prague, a knowledge of how long it was to sunset and the imposition of curfews in the city was useful knowledge. For instance – a simple glance at the dial indicating 19 hours tells you straight away that it is five hours to go before sunset.

As well as telling the time, the dial also has moving sun and moving effigies of the sun and moon, showing where in the zodiac they lie throughout the year. Useful astrological information.

The ecliptic circle with the zodiac signs and the sun and moon effigies rotate together once per day, but gradually over the course of the year, the sun and moon effigies with make a complete circle of the zodiac.

All this is achieved by some sophisticated gearing located behind the dial and driven by the clock mechanism in the tower. With the horizon circle with shaded buff areas, the periods of Aurora and Crepuscular, dawn and dusk are also shown,

Today, the clock is controlled by a more modern ‘regulator clock made by Romuald Bozek in the 1860s, but for the most part, the clock mechanism is still that which has been in existence from the beginning of its history.

Looking at the illustration here, you will see that the time is just a few minutes past 13 hours. On the fixed chapter circle the time is shown just before IX o’clock in the morning and hour 24 is just before 8 o’clock in the evening – correct for a July date. The sun is in Leo and the moon is in Aries.

So next time you stand in front of this amazing clock, you can really show off by knowing how to read the dial.