Cello inexpensive wood that has been blackened or "ebonized" to look like ebony, which is much harder and more expensive. Ebonised parts such as tuning pegs may crack or split, and the black surface of the fingerboard will eventually wear down to reveal the lighter wood underneath. Historically, cello strings had cores made out of catgut, which, despite its name is made from sheep or goat intestines which are dried out. Most modern strings used in the 2010s are wound with metallic materials like aluminum, titanium and chromium. Cellists may mix different types of strings on their instruments. The pitches of
Rackets (sport) covered racket court and is now the oldest surviving court in the world, as well as being the oldest indoor sports building in Scotland. It has been restored as a racket hall, but used as an exhibition area. Some private clubs also built courts. Along with real tennis and badminton, rackets was used as an inspiration for the game of lawn tennis, invented in 1873 by Walter Clopton Wingfield. A vacant rackets court built into the University of Chicago's Stagg Field served as the location of the first artificial nuclear chain reaction on December 2, 1942. The Stagg Field court