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Encyclopedia > Diptych
Ivory consular diptych of Areobindus, Byzantium, 506 AD, Louvre museum
Ivory consular diptych of Areobindus, Byzantium, 506 AD, Louvre museum

A diptych is any object with two flat plates attached at a hinge. Devices of this form were quite popular in the ancient world, types existing for recording notes and for measuring time and direction. The term is also used figuratively for a thematically-linked sequence of two books. Image File history File linksMetadata Download high resolution version (1500x1930, 2095 KB) Description Description: Ivory consular diptych of Areobindus, Byzantium, 506 AD, height: 1,1. Location: Louvre, Department of Decorative Arts, Richelieu wing, first floor (OA 9525) Photographer: Jastrow (2006) fr: Diptyque consulaire dAréobindus, Constantinople, ivoire, 506 ap. ... Image File history File linksMetadata Download high resolution version (1500x1930, 2095 KB) Description Description: Ivory consular diptych of Areobindus, Byzantium, 506 AD, height: 1,1. Location: Louvre, Department of Decorative Arts, Richelieu wing, first floor (OA 9525) Photographer: Jastrow (2006) fr: Diptyque consulaire dAréobindus, Constantinople, ivoire, 506 ap. ...


Note: This article discusses diptyches in the first sense. For paintings arranged in such a way, see polyptych. A polyptych (from the Greek polu- many + ptychē fold) generally refers to a painting (usually panel painting) which is divided into four or more sections, or panels. ...


Traditional diptychs are boxwood, with stamped hour lines and lacquered or varnished finishes. Some were also ivory (superior because it is easiest to read and less prone to wear than wood), or metal (sturdy, harder to read but less expensive than ivory).[1]

Contents

Writing Tablet

One form of diptych was like a shallow box. It had two wooden leaves with hollows on the inside edges, filled with wax, and space for a small wooden scriber. This permitted one to take waterproof notes in the wax without wasting money on paper. The wax could be smoothed and reused. It was probably excellent for shopping lists or other reminders.


It is in this form that the mention of "diptychs" in early Christian literature is found. The term often refers to official lists of the living and departed that are commemorated by the local church. The living would be inscribed on one wing of the diptych, and the departed on the other. The inscribing of a bishop's name in the diptychs means that the local church considers itself to be in communion with him, the removal of a bishop's name would indicate breaking communion with him. The names in the diptychs would be read publicly by the deacon during the Divine Liturgy (Mass). Diptychs were also used to inscribe the names of the saints. Although the wax tablets themselves are no longer used, the term is still used in the Eastern Orthodox Church to describe the contents of the diptychs, with all the same connotations. In a narrow sense, intercommunion is the same thing as open communion: the practice of serving communion to all Christians rather than only to those of ones own denomination. ... The word schism (IPA: or ), from the Greek σχίσμα, skhísma (from σχίζω, skhízō, to tear, to split), means a division or a split, usually in an organization or a movement. ... The Divine Liturgy is the common term for the Eucharistic service of the Byzantine tradition of Christian liturgy. ... Topics in Christianity Movements · Denominations Ecumenism · Preaching · Prayer Music · Liturgy · Calendar Symbols · Art · Criticism Important figures Apostle Paul · Church Fathers Constantine · Athanasius · Augustine Anselm · Aquinas · Palamas · Wycliffe Tyndale · Luther · Calvin · Wesley Arius · Marcion of Sinope Pope · Archbishop of Canterbury Patriarch of Constantinople Christianity Portal This box:      The Eastern Orthodox Church...


Sundial

The other form was a portable sundial. A face was on the inside of each leaf. One leaf formed a vertical sundial, the other a horizontal sundial. The shadow caster, or gnomon was a string between them, and calibrated how far open they should go as the angle is critical. Wall sundial-a vertical direct south dial Wall sundial in Warsaws Old Town- a vertical south west decliner dial A sundial is a device that measures time by the position of the Sun. ... The cantilever spar of this cable-stay bridge, the Sundial Bridge at Turtle Bay, forms the gnomon of a large garden sundial The gnomon is the part of a sundial that casts the shadow. ...


A sundial can be adjusted to any latitude by tilting it so its gnomon is parallel to the Earth's axis of rotation. However, the longitude is critical for an accurate local solar time, and is corrected by leveling the diptych on its axis from east to west.


If the hinge of the diptych is level with the ground (classically measured with a rolling marble in a slot), and both dials show the same time, the dials will show the apparent solar time, the hinge faces north (in the northern hemisphere), and the gnomon is parallel with the axis of rotation of the Earth.

Portable diptych sundial
Portable diptych sundial

Achieving all these functions is almost a lost art. A north-indicating diptych is possible only if the two sundials do not have the same complementary sun angle. The best real diptychs never consisted of two mirror-imaged 45 degree sundials; usually they were adjusted so that at the owner's latitude, the bottom leaf was level not just east-to-west, but north-to-south. That is, if the gnomon is not parallel to the earth's rotational axis, then since the two faces have different trigonometric projections, they will show different times. For example, if the gnomon deviates from the correct elevation angle at 9am or 3pm, each degree of error in the gnomon's elevation creates a difference of four minutes (one degree of angle) in the time readings of the two faces. However, at 6am, 6pm and noon, a deviation in the gnomon's elevation angle produces no change in times. Near noon, if the gnomon deviates from pointing north and south, the times of the two faces will deviate. At 6am and 6pm, deviations from north and south have no effect. Holding a diptych so that its gnomon-string is at the correct angle is often finicky, especially near sunrise, sunset and noon, so many later diptychs had magnetic compasses and plumb-bobs to help, but these were luxuries, not necessities. Image File history File links Download high resolution version (956x736, 476 KB) Licensing I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Image File history File links Download high resolution version (956x736, 476 KB) Licensing I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ...


Some diptychs also had rough calendars, in the form of pelikinons calibrated to a nodus in the form of a bead or knot on the string. These are accurate to about a week: Good enough to time planting of crops, but not as accurate as a well-kept calendar.


Some diptychs had compass roses (to measure bearings to geographic features) and latitude measurement bobs. Some authorities believe that large versions (a meter or more in width) were used for maritime navigation before magnetic compasses were well-known. Diptychs may thereby have come to acquire an air of magic in the ancient popular mind. Table of geography, hydrography, and navigation, from the 1728 Cyclopaedia. ...


Of course, all these functions could be combined in one pocket-sized artifact. Diptychs that combined writing and timekeeping often have a slot on one leaf to hold the gnomon. The gnomon can be detached from that end so the diptych can be opened completely for writing. On these the gnomon often has two knots, one for timekeeping and the other to latch the diptych shut and protect the wax. The "decorative" bead often seen on the end of extra-long gnomon cords may have been rolled in a slot, or dangled as a plumb-bob to determine if the diptych's hinge was level, or to measure latitudes.


It could be a very convenient thing to keep in one's pocket even in the current era, particularly in an area with few well-developed roads. Once a template is made for a current latitude, construction from nearly any available sturdy materials would be trivial.


References

  1. ^ Rose-Marie Hagen (2000), Masterpieces in Detail: What Great Paintings Say, Taschen, ISBN 3822813729, at 53

External links

  • National Gallery of Art, Prayers and Portraits: Unfolding the Netherlandish Diptych
  • Diptych The Catholic Encyclopedia, Volume V, Robert Appleton Company, Online Edition.
  • Diptych sundials, National Maritime Museum.
  • The Sundial Primer

  Results from FactBites:
 
Diptych - LoveToKnow 1911 (557 words)
The latter variety of diptych was inscribed with the magistrate's name and bore his portrait, and was issued to his friends and the public generally.
The insertion of a name on the diptych, thereby securing the prayers of the church, was a privilege from which a person could be excluded on account of suspicion of heresy or by the intrigues of enemies.
A third fold was consequently provided, and the tablet became a triptych (though the name diptych was retained as a general term for the object).
CATHOLIC ENCYCLOPEDIA: Diptych (1246 words)
diptychs are recognizable by their inscriptions or by the figure of the consul which they bear.
diptych, transformed in the eighth or ninth century; according to some it appears to be of ecclesiastical origin.
diptych leaf in the treasury of Tongres was evidently influenced by the carvings on the cathedra of St.
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