the carillon, in collaboration with Jacob van Eyck, into a full-fledged musical instrument by casting the first tuned carillon in 1644. The Hemony Brothers are regarded as the first of the modern western bell-founders who used a scientific approach to casting the optimum shape and tuning bells to harmonic principles. Materials Bell metal Bells for the intention of producing functional sound are usually made by casting bell metal, an alloy of bronze. Much experimentation with composition has existed throughout history; the bells of Henry II had nearly twice as much copper as tin, while much earlier Assyrian bronze bells had ten times the amount of copper to tin. The recognized best composition for bell metal though is a ratio of approximately 80 per cent copper and 20 per cent tin. Bell metal of these ratios has been used for more than 3,000 years and is known for its resonance and "attractive sound". Tin and copper are relatively soft metals that will deform on striking. By alloying, a harder and more rigid metal is created but also one with more elasticity than the use of one alone. This allows for a better resonance and causes the bell to "vibrate like a spring when struck", a necessary quality as the clapper may strike at speeds of up to 600 miles per hour. The forces holding the tin and copper together cause vibrations rather than cracks when the bell is struck which creates a resonant tone. This metal combination also results in a tough, long-wearing material that is resistant to oxidation and subject only to an initial surface weathering. Verdigris forms a protective patina on the surface of the bell which coats it against further oxidation. The hardest and strongest bronze contains large amounts of tin and little lead though an alloy with more than 25 per cent tin will have a low melting point and become brittle and susceptible to cracking. This low melting point proved to be the nemesis of Russia's third attempt at casting the Tsar Bell from 1733 to 1735. The bell was never rung, and a huge slab cracked off (11.5 tons) during a fire in the Kremlin in 1737 before it could ever be raised from its casting pit. Burning timber fell into the casting pit, and the decision was whether to let it burn and risk melting the bell or pour water on it and risk