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Since bell makers used
to engrave dates (or year of manufacture) on the bell, it has been
possible to trace some of the oldest bells. The Bell of St. Patrick,
found in Great Britain is said to have belonged to Saint Patrick. In
Germany, a bell in Drohndorf dates back to 1098, while one found in
Pisa, Italy is said to be marked 1106.
How are bells made?
Huge bells such as bells and carillons are generally molded in
a single piece from a molten metal called Bell metal, which is a
mixture of copper and tin. The ratio of copper to tin is thirteen to
four.
For casting a bell,
either two moulds of baking clay or one mould of baking clay and one
mould of iron is used. Iron has a higher melting point than bell
metal. One of the moulds forms the open space inside. This is the
solid inner mould. The outside of the bells is shaped using a hollow
outer mould. The outer mould contains holes for gases to escape, in
order that there are no bubbles in the bell.
In the next stage,
molten liquid is poured between the two moulds and is left to cool
and become hard. When the bell is ready, the clay moulds are thrown
away.
Well known bells
The Big Ben that hangs in the
Westminster clock tower of the Houses of Parliament of London and
the Liberty Bell of America are two very famous bells. |
