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Medieval Mass Dials, Do You Know What They Are?

Mass dials, also known as ‘scratch dials’ or ‘service dials’ after the Reformation, are a type of medieval dial found on the south side of many churches across the UK dating between 1100 and 1600. They were used to show the time of the Mass hence the name. The alternative moniker, scratch dials, refers to the fact that some of these dials are etched quite crudely, literally as if someone has scratched them into the stonework.


How do Mass Dials work?

A mass dial is scratched or etched into the stonework and is roughly the size of a side plate. In the centre of the dial is a hole that would have been home to a horizontal metal or wooden rod set at right angles to the church wall and which was used to cast a shadow.

The shadow crossed the scratched or carved lines that radiated from the central point of the dial and hence it was possible to determine the time of day. The rod was called a gnomon. Sometimes, the hole for the gnomon was found in the mortar between two blocks of stone in the same block as the dial or in the one above.

Centuries after last being used, we got this medieval mass dial working again – just by using a stick as a gnomon…

The Anglo-Saxons divided what we know now as the 24-hour period into eight sections called Tides or ‘Tid’ in Old English. The four daylight divisions were called: –

  • Morgen – around 6 am to 9 am
  • Undern – 9 am to noon
  • Middaeg – noon to 3 pm
  • Gelotendaeg – 3 pm to 6 pm

By the Norman period, the day had been divided into 12 hours.

Mass Dials is a Bit of a Misnomer

mass dial
Very rare and one of the finest in the country, this circular Saxon dial is surrounded by four ‘lobes’ and four 3-leaved ornaments. There are five tide marks, two with clear crosses (tides being the Saxon unit of time, averaging 3 hours. The word ‘tide’ was used to denote a time period and survives in the English language to denote special times such as ‘eventide’ or ‘yuletide’). This amazing example is found at Corhampton, Hampshire.

From 1100-1600, the dominant or only church in the UK was the Roman Catholic church. Many of the most ancient medieval churches in the British Isles, date to this time so the word ‘Mass’ is quite correct, but mass dials were not just used to pinpoint a sole religious service once a week.

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The daily religious calendar was dominated by something called the Divine Office and so there were different liturgical services at all sorts of times every day. Prayers were said all day beginning with Matins which was before dawn and then progressing through Prime, Terce, Sext, None, Vespers at sunset, and Nocturnes after sunset.

Saxon sundial
This Saxon dial is made from red sandstone. This part of Hampshire is chalklands thus this dial isn’t local – so where did it come from?

Add into the mix the fact that there was no universal system of timekeeping and telling the time plus, the majority of people were largely illiterate which is why the church relied on so many visual images like stained glass windows to tell the story.

Medieval society used the Julian calendar system to calculate the day. The Julian system has three significant dates in each month and the remainder of the days are worked out around these. However, the daily cycle of time for religious purposes was calculated using the mass dial, developed originally by the Anglo-Saxons.

Mass Dial
A well worn mass dial

Where are Mass Dials Located?

Mass dials are usually quite small and can be found in different locations on the south side of a church including the wall and the buttresses. They can also be found on the quoin or smooth cornerstone of the tower, nave, or chancel or above a porch, door, or window. Commonly, they are found near the main door or the priest’s door. The south location was to catch the sun and they are usually at eye level.

In the 14th and 15th centuries, many churches were enlarged and so some mass dials disappeared from view or were moved, even to the north wall where clearly, they were classified as redundant. This didn’t matter so much as there was more reliance on mechanical clocks by this time. If a mass dial is found in a location other than the south elevation then this indicates that it has probably been moved and often by Victorian restorers.

Mass Dial
Nice example of a mass dial facing south at St James’s church, Upper Wield, Hampshire. Along with plenty of graffiti.

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Sometimes, a mass dial was rebuilt into the church fabric upside down so they could never be readable again. Other examples show mass dials inside a porch over the south door, the porch being a later addition.

Regional Differences

Mass dials vary quite significantly depending on their location and their survival depends upon what seems to be a large amount of luck.

Early mass dials are usually a half-circle design of dots with three radiating lines to give the times of the services. There is an example of one such mass dial at St John Jerusalem at Sutton-at-Hone in Kent, a Knights Hospitaller Commandery. Some mass dials have evidence of runic inscriptions whereas others have Roman numerals, added to show the division of hours although these are quite rare. Later designs feature complete circles.

A mass dial tended to reflect the local knowledge of the parish priest when it came to specific design and complexity.

Time differed across the UK so local time was used for each church and if the sun didn’t shine for a few days, then this could prove challenging! Some counties seem to have few mass dials or at least, there are few remaining, for instance, West Yorkshire and Lancashire, whereas others like Kent, Lincolnshire, and Gloucestershire have plenty of examples.

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GMT appeared in the UK as late as 1880 as a response to the arrival of the railways which required some form of standard time in order to run a coherent timetable.

Mass Dials and Clocks

Some mechanical clocks had appeared by the 14th century with the introduction of a 24-hour time period, but they seemed to run alongside the old medieval system of mass dials.

Mass dial
A mass dial that has had its centre filled in. Not sure why…

The understanding of the rotation of the sun to the earth’s axis was continuing to develop and from this, the real sundial appeared, with the gnomon aligned to the true celestial north in relation to the local latitude. The lines on the vertical sundial were graduated to provide an accurate time and this increasingly sophisticated time-keeping instrument overran the humble mass dial in a pincer movement, with the development of the mechanical clock.

What we don’t know about Mass Dials

Most people accept that mass dials are an early type of sundial but this doesn’t cover every example of their appearance. For instance, some people question the removal of mass dials to the north wall as more than renovation, that they were placed there intentionally, and what about churches where there is more than a mass dial in the same location?

There are examples, such as the church of Worthing in the Wensum Valley in Norfolk. Worthing Church is one of Norfolk’s round tower churches with many early Norman features. There is a late medieval porch covering a beautiful early Norman doorway in which there are at least three carved mass dials. Whilst theorists don’t deny that the porch appeared after the mass dials, why are there three that seem to be identical?

There are also examples of multiple dials set on the north side of the church which rather challenges the theory that these have all been moved due to renovation or development of the church fabric down through the centuries. One perhaps but several?

12th Century

Some churches have more than one mass dial with a total of eight recorded on the medieval church of St Margaret at Hales in Norfolk. St Margaret’s has been cared for by the Churches Conservation Trust since 1974.

It has a round tower and a reed thatched roof and is more or less unchanged since the 12th century apart from rebuilding the top part of the tower in the 14th century. There are several mass dials and votive crosses on the door jambs plus more examples on the southwest quoin. Why so many? Unfortunately, due to some quite extensive vandalism in January 2022, St Margaret’s is now closed until further notice.

Rarely, a mass dial can be seen on a house but this is usually explained by the presence of a local former church that has fallen into disuse or collapsed and the stone taken away by villagers for other building projects.

Interested parties can cite numerous examples where the type, number, or location of mass dials just don’t fit the accepted pattern so there are perhaps many more questions to be answered about this medieval graffiti over and above their accepted use as early timepieces.

The British Sundial Society and Conservation

Many mass dials are of a great age now and have been exposed to weathering, vandalism, and some crafted vandalism – or should that be renovation? Even plant growth and the dreaded ivy have an impact so suffice to say, many mass dials are only barely discernible in the 21st century.

The British Sundial Society is making an attempt to log mass dials and, in some locations, they are the object of a conservation scheme, appropriate to the area and the type of stonework. Usually, a conservation architect is appointed by the church diocese to review and report on a particular mass dial and whether any intervention is warranted.

The church of Saint Mary, Breamore, Hampshire

Around 3,000 mass dials have been recorded by the British Sundial Society but there are still plenty out there and the British Sundial Society is happy to take recordings from the public, preferably with a good photographic image and the name and address of the church. The BSS has a Mass Dials Registrar responsible for collating any reports and there is a also a mass dial report form on their website.

For those who are just interested in seeing what’s out there, the BSS has a concise version of the Mass Dial Register available either as a DVD or in booklet form from their online shop.