Science Fair Project Encyclopedia
A glass harmonica is a type of musical instrument that uses nested glass bowls to produce musical tones. It was invented in 1761 by Benjamin Franklin. Mozart was so enthralled by its sound that he composed several pieces for it.
History and legend
The instrument became immensely popular but also developed a disturbing reputation. The sounds of the glass harmonica, though praised by many (Thomas Jefferson called it the "greatest gift offered to the musical world of this century"), were also blamed for nervous disorders in some listeners. The instrument was even banned in one German town when a child's death was attributed to it. Franz Mesmer used the instrument to condition his subjects, which added to its mystical reputation. Legends of the effects of the glass harmonica became so bizarre that a German glass harmonica instruction manual from the 1700s specifically states that the sound of the instrument will not bring the dead back to life. As a result of the instrument's bad press it fell out of favor for many years, until being practically reinvented by a German maker of scientific glass in the early 1980s.
The modern glass harmonica is made from quartz in the shape of a long cylinder, heated to 1700 °C or 3100 °F and blown out into a special shape, which is then cut in half, producing two bowls. In the 18th century, 40% lead glass was used, The bowls were worn and tuned with an emery grind wheel . As the depth of a bowl decreases, the pitch becomes higher. Sometimes, the seven colors of the rainbow were used to symbolize the seven diatonic degrees , black figuring the inflected notes. Modern manufacturers use transparent glass and gold for the brims of the bowls corresponding to the black keys of a keyboard, as Rollig did in the 18th century. Previously, cheaper lead had been used instead of gold, leading to lead poisoning of those who played it regularly, absorbing it through their wet fingers.
Glass harmonicas belong to the family of idiophone rubbed instruments. The glasses start vibrating according to the relaxation principle : when a finger rubs a bowl, it alternately catches and releases. This creates a series of impulses which set the bowl into vibration. The phenomenon is complex, so the glass-blower must be very gifted to give the instrument its personality, as the tone, the mode and the harmonic composition of the bowls depend on a large number of parameters. Thus, two bowls giving the same note will have different tones according to the materials used, to their shapes, their thicknesses, their dimensions, their hidden defects.
When Benjamin Franklin invented the instrument, he called it "armonica," based on the Italian word "armonia" which means "harmony." The reeded mouth instrument "harmonica" wasn't invented until the next century, over fifty years later. Over the years Franklin's name for the instrument has been largely replaced by glass harmonica.
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