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mathematics

Sunwise

Sunwise is a mathematics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Sunwise rather than just read about it. In short: Sunwise, sunward or deasil (sometimes spelled deosil), are terms meaning to go clockwise or in the direction of the sun, as seen from the Northern Hemisphere. The opposite term is widdershins (Middle Low German), or tuathal (Scottish Gaelic).

Sunwise — main illustration
Sunwise — illustration

Key takeaways

  • Sunwise belongs to mathematics; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Sunwise to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Sunwise from memory before moving on to harder problems.

Reference excerpt

Sunwise, sunward or deasil (sometimes spelled deosil), are terms meaning to go clockwise or in the direction of the sun, as seen from the Northern Hemisphere. The opposite term is widdershins (Middle Low German), or tuathal (Scottish Gaelic). In Scottish culture, this turning direction is also considered auspicious, while the converse is true for counter-clockwise motion.

Irish culture

During the days of Gaelic Ireland and of the Irish clans, the Psalter known as An Cathach was used as both a rallying cry and protector in battle by the Chiefs of Clan O'Donnell. Before a battle it was customary for a chosen monk or holy man (usually attached to the Clan McGroarty and who was in a state of grace) to wear the Cathach and the cumdach, or book shrine, around his neck and then walk three times sunwise around the warriors of Clan O'Donnell. According to folklorist Kevin Danaher, on St. John's Eve in Ulster and Connaught, it was customary to light a bonfire at sunset and to walk sunwise around the fire while praying the rosary. Those who could not afford a rosary would keep tally by holding a small pebble during each prayer and throwing it into the bonfire as each prayer was completed. Similar praying of the rosary or other similar prayers while walking sunwise around Christian pilgrimage shrines or holy wells is also traditional in Irish culture during pattern days.

Scottish culture This is descriptive of the ceremony observed by the druids, of walking round their temples by the south, in the course of their directions, always keeping their temples on their right. This course (diasil or deiseal) was deemed propitious, while the contrary course is perceived as fatal, or at least unpropitious. From this ancient superstition are derived several Gaelic customs which were still observed around the turn of the twentieth century, such as drinking over the left thumb, as Toland expresses it, or according to the course of the sun. Similarly to the pre-battle use of the Cathach of St. Columba in Gaelic Ireland, the Brecbannoch of St Columba, a reliquary containing the partial human remains of the Saint, was traditionally carried three times sunwise around Scottish armies before they gave battle. The most famous example of this was during the Scottish Wars of Independence, shortly before the Scots under Robert the Bruce faced the English army at the Battle of Bannockburn in 1314. Martin Martin says:

Some of the poorer sort of people in the Western Isles retain the custom of performing these circles sunwise about the persons of their benefactors three times, when they bless them, and wish good success to all their enterprises. Some are very careful when they set out to sea, that the boat be first rowed sunwise, and if this be neglected, they are afraid their voyage may prove unfortunate. I had this ceremony paid me when in Islay by a poor woman, after I had given her an alms. I desired her to let alone that compliment, for that I did not care for it; but she insisted to make these three ordinary turns, and then prayed that God and MacCharmaig, the patron saint of the island, might bless and prosper me in all my affairs. When a Gael goes to drink out of a consecrated fountain, he approaches it by going round the place from east to west, and at funerals, the procession observes the same direction in drawing near the grave. Hence also is derived the old custom of describing sunwise a circle, with a burning brand, about houses, cattle, corn and corn-fields, to prevent their being burnt or in any way injured by evil spirits, or by witchcraft. The fiery circle was also made around women, as soon as possible after parturition, and also around newly-born babes. These circles were, in later times, described by midwives, and were described effectual against the intrusion of ‘daoine-sìth’ or ‘sìthichean’, who were particularly on the alert in times of childhood, and not infrequently carried infants away, according to vulgar legends, and restored them afterwards, but sadly altered in features and personal appearance. Infants stolen by fairies are said to have voracious appetites, constantly craving for food. In this case it was usual for those who believed their children had been taken away, to dig a grave in the fields on quarter-day and there to lay the fairy skeleton till next morning, at which time the parents went to the place, where they doubted not to find their own child in place of the skeleton. The use of the sunwise circle was also traditional in the Highlands during Christian pilgrimages in honour of St Máel Ruba, particularly to the shrine where he is said to have established a hermitage upon Isle Maree.

"Deosil" and other spellings Wicca uses the spelling deosil, which violates the Gaelic orthography principle that a consonant must be surrounded by either broad vowels (a, o, u) or slender vowels (e, i). The Oxford English Dictionary gives precedence to the spelling "deasil", which violates the same principle, but acknowledges "deiseal", "deisal", and "deisul" as well.

Other cultures This distinction exists in traditional Tibetan religion. Tibetan Buddhists go round their shrines sunwise, but followers of Bonpo go widdershins. The former consider Bonpo to be merely a perversion of their practice, but Bonpo adherents claim that their religion, as the indigenous one of Tibet, was doing this prior to the arrival of Buddhism in the country. The Hindu pradakshina, the auspicious circumambulation of a temple, is also made clockwise.

See also Circumambulation

References

Sources This article incorporates text from Dwelly's [Scottish] Gaelic Dictionary (1911). (Deiseal)

Worked examples

Example 1 — a first encounter with Sunwise

Start with the simplest possible case. Write down what Sunwise claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Sunwise before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Sunwise ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Sunwise

In research
Sunwise appears in mathematics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Sunwise in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Sunwise is common in secondary-school and first-year university syllabi. It links to neighbouring topics Catholic Church in Ireland, Celtic Christianity, History of Catholicism in Scotland, so understanding it makes those chapters shorter.
In everyday life
Look for Sunwise outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Sunwise in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Sunwise means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Sunwise out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Sunwise in simple terms?

Sunwise, sunward or deasil (sometimes spelled deosil), are terms meaning to go clockwise or in the direction of the sun, as seen from the Northern Hemisphere. The opposite term is widdershins (Middle Low German), or tuathal (Scottish Gaelic).

Why does Sunwise matter?

Because it connects several mathematics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Sunwise?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Sunwise.

Tags

  • Catholic Church in Ireland
  • Celtic Christianity
  • History of Catholicism in Scotland
  • Irish folklore
  • Irish mythology
  • Orientation (geometry)
  • Roman Catholic pilgrimage sites in Ireland
  • Scottish folklore
  • Tibet

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