Sept/Oct 2007


History of metal casting (Part 2)

By F. Habashi

Casting of Bells

The development of the bell-casting skill ushered in the Bronze Age around 3,000 BC. Bells were frequently buried in the tombs of Chinese royalty and noblemen, but not in ancient Egyptian tombs. As metal-casting techniques improved, the size of bells increased; bells weighing many tonnes were suspended in front of temples and palaces. Both drums and bells announced the time of day and warned of fires, floods, or an approaching enemy. The ancient Chinese were also successful in controlling the pitch of bells by controlling the relationship between size and thickness.

Chinese bells were cast in a variety of forms. In addition to stationary bells, small ornate hand bells with clappers were used in temple ceremonies. These are rung by Buddhist and Taoist priests during services, in conjunction with cymbals, gongs, and other instruments. It was believed that bells could cast or remove a spell and increase fertility. Muslims and Jews have refrained from using bells. Muslims associated bells with pagan rites and beliefs, while in Judaic practice, the ram’s horn and the metal trumpet have always been used. The casting of large temple bells in China reached its zenith during the Ming dynasty (1368-1620). The largest such bell, cast during the reign of the Emperor Yon-gle (1403-1424), weighed 52 tonnes.

Because bells were utilized so much in pagan cultures, Christendom initially disapproved of them. It was not until the second century that the bell was adopted as the symbol of preaching the gospel and used as a call to assemble. The popularity of bells increased enormously in the ninth century after being promoted by Charlemagne. One of the earliest works describing the casting of bells and the problems of its harmonics was written by the Benedictine monk Theophilus Presbyter in the latter part of the eleventh century. This work and subsequent treatises indicate the concern for proportions and the proper mixture of copper and tin for producing the best ring, and how to change a bell’s pitch by varying its dimensions and wall thickness. Since the fifteenth century, it has been possible to influence the musical tone of the bell through precise design of its form. When larger bells were required, it became imperative to cast them in the church yard to eliminate their transport.

The Casting Method

For casting large bells, the moulds were formed in deep pits directly in front of the furnace to simplify the pouring process. The process first called for the preparation of the core, usually formed with vertical sweeping, which consisted of a top and bottom bearing, the latter supporting a spindle on which the strickel board was mounted. The board was shaped to the interior contour of the bell. Loam, based on a brick interior, was plastered on until the board could be revolved with clearance. A new board was placed on the spindle, shaped to the outer contour of the bell. Clay was again added until the outer shape was attained. Rods were placed in the mould for reinforcement and the entire mould baked. When the bells were cast, the molten metal was directed through a trough from the furnace into the gates. After cooling, the castings were removed.

Famous Bells

The Peace Bell, which weighs more than a tonne, is located in Peace Park in central Hiroshima. It is rung by visitors as part of their wish for peace. Just outside Sofia, Bulgaria’s capital, is the Bell Garden containing a large number of bells donated by different countries.

The Liberty Bell [pictured, left]

In 1751, the Pennsylvania Assembly ordered a bell from a foundry in England to commemorate the 50th anniversary of William Penn’s Charter of Privileges, Pennsylvania’s original Constitution, which speaks of the rights and freedoms of people. The bell, however, cracked on arrival. It was then given to a Philadelphia foundry for recasting. When the new bell was raised in the belfry, apparently nobody was pleased with its tone and so it was sent back to the foundry for recasting. The new bell, weighing 2,080 lb, cracked in 1846. It achieved special status when abolitionists adopted it as a symbol for the movement.

Big Ben

After a fire destroyed the Palace of Westminster, the seat of the British government, Parliament decided in 1844 that the new building should incorporate a tower and clock. The clock was completed and the bell was cast in 1858; it weighed 13.76 tonnes. The Parliament had a special sitting to decide on a suitable name for the great bell. During the debate and amid the many suggestions that were made, Sir Benjamin Hall, a large and ponderous man known affectionately in the House as “Big Ben,” rose and gave a long speech on the subject. When he finished, a wag in the chamber shouted out: “Why not call him Big Ben and have done with it?” The house erupted in laughter and the name ‘Big Ben’ had been adopted.

Russian Bells

After his marriage in 1472 to Sophia (Zoe) Palaeologus, niece of Constantine XI, the last Byzantine emperor, Ivan III took interest in the development of the Kremlin. In 1474, he invited a group of skilled workers from Italy to introduce the Western techniques of casting. By 1533, an 18-tonne bell was cast in the Kremlin. The seventeenth century was the greatest period of Russian bell casting. In Moscow and its suburbs there were about 4,000 churches, each having up to as many as ten bells. On Paschal night, it was customary for the bell in the Tower of Ivan the Great to strike the first sound at midnight, followed by the ringing of the bells of all the other churches, announcing the Resurrection of Christ.

The giant bell on display in the Moscow Kremlin is actually the last of the four bells that bore the nickname “Tsar-Kolokol” or “Tsar-Bell.” It was cast in 1599 during the reign of Boris Godunov and weighed 35 tonnes; however, it fell during a fire near the middle of the seventeenth century. Its metal was used in the casting of a second bell in 1654 that weighed 128 tonnes; however, it cracked as well and fell into pieces when first tested. It was again re-cast a year later, this time weighing 160 tonnes, but another fire caused it to fall down and crack in 1701. In 1730, Empress Anna Ivannovna gave the order to re-cast the remains of this bell into a new 220-tonne bell; however, while it was in the pit, the scaffolding caught fire in 1737 and the bell fell. People started to pour water over it and as a result, the bell cracked and a big chunk fell off.

By the mid-eighteenth century, the expansion of Russia to the east caused an increase in the demand for church bells in newly developing villages, towns, and cities. Also, a new bell industry had emerged, that of small bells for horse carriages. Farmers along the new travel routes to Siberia started to cast horse bells in their farmyards. At annual fairs, hundreds of bells were put on display, suspended from scaffolding so that the customers could ring the bells and buy the ones to their liking. During World War I, over a hundred bells were sent from churches in the Baltic provinces and Poland to save them from the advancing Germans. Russian bell founding ended after the October Revolution in 1917. The state confiscated church bells and many were sold.

Other Bells

The oldest bell in Korea was cast in 723 AD in the Shilla Dynasty. King Sung-Tug’s Great Bell was cast in 771 AD in the Chosen Dynasty and weighed about 22 tonnes; it is on display at the National Museum in Seoul. Korean bells were struck by wooden hammers.

The Great Bell of Dhammazedi in Burma (now Myanmar) may have been the largest bell ever made. It was lost in a river after being removed from a temple by the Portuguese in 1608. It is reported to have weighed about 300 tonnes. One of the largest bells still in existence may be the Mingun Bell, located in the Mingun temple, Myanmar, which weighs 90 tonnes.

The bell in St. Stephen’s Cathedral in Vienna was cast in 1711 from the metal of cannon iron balls used by the Turks during the siege of the city in 1683; it weighed 22.5 tonnes and was destroyed during World War II when the cathedral was damaged by fire. The new bell weighs 21.4 tonnes, was cast from the metal of the old bell in 1951 in the St. Florian foundry in Upper Austria, and was ceremonially transported from Linz to Vienna. It is popularly called “Pummerin” because of its deep tone. It is the largest bell in Austria and the second largest in Europe, after the one in Cologne cathedral.

Bell Museum

In 1599, Bartlme Grassmayr established the Bell Foundry in Innsbruck, Tyrol. His casting expertise was continually improved and handed down from father to son. The foundry museum relates the history of bell casting.

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