VISITING AUTHOR-ARTICLE

MARCH 2011

 The Lewis Chessman

Forwarded by Thomas B. Cole, M.D., MPH., JAMA 

Page 649   JAMA, February 16, 2011—Vol 305, No. 7

          THE NORSE SEAFARERS OF THE MIDDLE AGES, ALSO KNOWN as the Vikings, explored Greenland and North America, plundered towns and monasteries along the coasts of Europe, and established trade routes throughout the western world. One of their trade routes stretched east by water from Norway to the Gulf of Finland, then overland and downriver through present-day Russia and across the Black Sea to Constantinople, capital of the Byzantine Empire. Another route led to the Hebrides Islands off the west coast of Scotland, where a collection of 93 game pieces of Norse origin was found on the Isle of Lewis in 1831. Most of the pawns were missing, but there were almost enough face pieces to make up four complete chess sets. The pieces may have been buried in the dunes by a merchant or by a person of high rank who hid the sets during a time of conflict between local rulers and their Norwegian overlords.

          Nine of the Lewis chess pieces are displayed on the cover. The rounded arches of the helmets and flowing, leafy scroll­work are characteristic of the Romanesque style of European art. The chess pieces may have been carved in Trondheim, the political and cultural center of Norway at the time, using walrus ivory from Greenland. The design of each piece reflects its status in medieval society and on the field of play. The pawns, faceless in this set, are analogous to vassals or serfs. They are the most numerous of the chess pieces but have the least tactical value. Next in importance are the knights on horseback, most useful in the early phase of the game when many pieces remain in play, because they can leap over other pieces to control the center of the board and limit the opponent's freedom of movement. In the center of the group is a bishop with his prayer book and staff. Bishops are most effective at the end of die game, when fewer pieces remain on the board to obstruct their long diagonal movements.

        To either side of the bishop are the warders, who defend the fortifications. One of the two warders is a berserker, a type of specialist in Norse combat units who would become so enraged during battle that he would bite his shield and attack anyone within reach, whether friend or foe. Some berserkers led assaults and others served as bodyguards. Instead of warders, modern chess sets have pieces that look like castle towers, called rooks, to symbolize their defensive role. Between the pawns in the grouping on the cover sit the king and the queen on their thrones. In chess, if a king is attacked and cannot escape, the game is over. The steely king on the cover grips his short sword in both hands, as if to say he will go down fighting. The queen has more freedom of movement, and is therefore more dangerous, than all of the other chess pieces; but conversely, the loss of the queen to an attacker is a severe handicap to the player. No wonder she looks so anxious and careworn.

          As the tactics of chess have evolved, the style of play has often reflected the social values of the players. An early version of chess was played in the Sassanid Empire of Persia, perhaps as long ago as 600 CE. After the Muslim conquest of Persia in the seventh century, chess spread throughout the Muslim world and via trade routes to Christian Europe. In the Middle Ages, chess was a popular pastime of European nobility, along with riding, archery, hawking, and the writing of verse, but players were discouraged from spending the time to become adept at chess, because it was, after all, only a game. In the Age of Enlightenment, chess was considered to be an exercise in moral development; the American author and political theorist Benjamin Franklin wrote that playing the game was a way to acquire the virtues of foresight, circumspection, and caution.

         By the 19th century, chess had become an everyman's game, with more matches played in coffeehouses than in palaces or landed estates. Players with exceptional skill emerged, and tactical innovations were publicized in books and journals. Chess masters of the early 19th century were most admired for their ability to probe weaknesses in the opponent's position. Players typically used one or two pieces to mount a quick attack on the opposing king, without first taking the time to move other pieces into positions of support. To counter these tactics, more analytic players shored up their defenses. In the 20th century, combinations of moves were planned even further ahead to establish positional strength and enable coordinated attacks. At the expert level, the emphasis today is on refining a winning strategy, rather than on taking pride in a culturally commendable or entertaining style. Still, there is a place for beauty in the choreography of chess. Tacticians who specialize in creating series of moves leading to specific outcomes are called chess composers, and their compositions are played, like musical scores, by students of the game.

Studying and conserving the Lewis Chessmen

          The hoard of 82 ivory chess-pieces known as the Lewis Chessmen was found in 1831 in Ulg on the Isle of Lewis in the Outer Hebrides in what was possibly a small, drystone 'subterranean' chamber.

          The pieces consist of elaborately worked walrus ivory and whales' teeth in the forms of seated kings and queens, mitred bishops, knights on their mounts, standing warders and pawns in the shape of obelisks.

          When found, some were reported to be stained red. Recent examination by British Museum scientists and conservators using optical microscopy did suggest possible traces of red coloration on some pieces, but further investigation has not been able to detect any colourants still present.

          Ivory is very similar to bone in composition, consisting of a mixture of organic and inorganic materials: the inorganic part consists of calcium phosphate in association with carbonate and fluoride (hydroxyapatite). The organic material is mainly the protein ossein. Distinguishing between ivory and bone, and determining the type of ivory used requires expert examination using a microscope.

Identification of the ivory of the Lewis chessmen

          Scientific examination of the Lewis chessmen is ongoing, but recent investigations at the British Museum have been focused on identifying how they were shaped and decorated, and what they are made of.

          Using a variable pressure scanning electron microscope (SEM), scientists at the Museum can see traces of wear and modifications caused by burial and damage.

          Some of the chessmen are made from whale tooth but most are made from walrus ivory, the long upper canine teeth of the Atlantic walrus. Teeth and tusks have the same physical structures, which consist of the innermost pulp cavity, dentine, cementum and outermost enamel.

          Walrus ivory structure consists of outer hard yellowish-white enamel, cementum and two distinct inner layers of calcareous dentine. The image below shows this unique structure: the primary dentine has fine concentric rings whereas the innermost core of secondary dentine, which is spongy in appearance but is as hard as the primary, has a more globular texture, sometimes described as marbled. The original carvers have maximised the use of the smoother primary dentine for the carving.

          Because of its colour, old walrus ivory is reputed to be more valuable and sought after for carving than fresh material. The same structure is present in both fresh and old walrus ivory; both can be carved in the same way. SEM examination shows that many of the Lewis chessmen are made of old walrus ivory. The ivory has been damaged by marine gastropods, indicating the walrus was long dead when the tusks were collected.

          Some of the chessmen are made from whale tooth. Whales have conically shaped teeth with a small amount of enamel at the tips. The rest of the tooth is covered by a substance called cementum. The dentine is deposited in parallel layers which shows up as concentric rings.

          The structure of walrus ivory (and whale tooth) differs markedly from that of elephant ivory. Polished cross-sections of elephant ivory dentine display uniquely characteristic Schreger lines, often referred to as intersecting arcs or engine-turnings.

          All the Lewis chessmen have recently been examined by British Museum conservators to investigate their condition and carry out any treatment required for them to be safely displayed.

          Some of them have undergone minor conservation treatments over the years since their discovery to stabilise them but on the whole are in relatively good condition. In some cases these old coatings and adhesives had changed with time and become more noticeable or had degraded leaving unsightly remains visible on the surface.

          Ultraviolet light was used to reveal further evidence of old treatments not visible in normal light. The materials used in these previous treatments have been characterised and documented, and provide an insight into changing approaches to the selection of conservation materials over the last century.

          Walrus ivory has a distinctive structure with two distinct inner layers of dentine, which affects the way in which it deteriorates and this in turn affects the approach to its conservation. In a few cases there was evidence of old movement such as cracks and breaks between the primary and secondary dentine.

          Light cleaning and some stabilization was needed. Splits and cracks were treated with a dilute adhesive and areas of loss filled. Only adhesives and fill materials stable, reversible and also flexible enough to accommodate slight size changes in the ivory, were used.

As a very sensitive material, prolonged exposure to water can leave ivory brittle and chalky, while acids readily attack it. It also reacts to changes in the moisture content of the air. If the humidity in the environment drops, the ivory loses moisture and contracts. If the humidity increases, it absorbs moisture and expands. Fluctuations in humidity (or exposure to heat) can cause ivory to crack, split or warp, so the chessmen are kept in a stable environment of about 40-55% Relative Humidity and at a temperature of 16-20 ºC.

          It is likely that some of the chessmen were once coloured although analysis has not been able to detect any colouring agents still present. Nevertheless, since some colourants are light sensitive, the lighting within the display-case is kept at a low level, so any remaining colour will be preserved.

Bishop	King	Warder