wobble board

The angle at which the board is held, and the way the board is "flicked", can alter the timbre of the sound produced. It is similar to the thunder sheet, a metal instrument used to imitate the sound of thunder in 18th century theatre.

• Illustration — The wobble board was invented and popularised by Rolf Harris According to an interview he gave to Tony Barrell for The Sunday Times Magazine in 2001, Harris discovered the musical properties of hardboard by chance in 1959, when he was about to paint a portrait of the conjurer Robert Harbin. Before his subject arrived, Harris prepared the background, covering a large piece of hardboard with Prussian blue oil paint mixed with turpentine. But the surface refused to dry. "It was all sticky and nasty. He was due to arrive in about half an hour." In desperation, Harris propped the board over a paraffin heater. When he touched it later, it was so hot it burned his finger. "So I propped it between the palms of my hands and shook it to cool it down. And... I thought, 'What a marvellous sound. Rolf Harris said: Official Rolf Harris wobble boards were sold commercially for a time in the 1970s but most were made by the player. Almost any large, springy and flexible sheet of material can be used as an impromptu wobble board, although some materials are markedly better than others. Harris's instrument was originally made from a type of wood composite known as hardboard (Masonite in the United States and Australia). Two wobble boards donated by Harris were part of the National Museum of Australia collection before they were removed in the light of his arrest for indecent assault in 2013.