Alastair Galbraith playing the glass harmonium (Both photos: Alister Reid)
With laboratory glass, and the talents of glass-blower Anne Ryan from the University of Otago, Alastair Galbraith has created a musical instrument called a glass harmonium. The first mechanical glass harmonica was invented by Benjamin Franklin and composers like Wolfgang Amadeus Mozart wrote pieces specifically for the instrument. Watch some of the glass being blown for the glass harmonium:
Glass “bowls” are arranged with smallest on the left, to largest on the right, with a sewing machine treadle to spin the rod, like a rotisserie. The sound produced is similar to the sound of running a finger around different-sized wine glasses.
Alastair Galbraith plays the instrument by dipping his fingers in a mixture of lemon juice and water to stop grease accumulating on the glass.
He also demonstrates some aluminium rods, which sing when squeezed the right way. The rods have to be held with one hand, either in the exact middle or at specific points along the rod, and then squeezed with the fingers of the other hand after being dipped in sticky violin rosin. The motion causes a longitudinal wave, vibrations which travel the length of the rod.
Find out how these waves create sound.