Trivia Advent Calendar

[Eva Elisabeth]

#18 is easy, no?
   

Thomas, your comment to Gene made me curious. Didn't check disco invention (guess you are correct), but disco ball, and Wiki reads:
"What are now sometimes called 'disco balls' were first widely used in nightclubs in the 1920s. They were already in existence and use before then, appearing in a description of a ballroom dance in 1897 in Boston." This picture shows the Lousoana Five jazz band in 1919 (see in the middle of the upper margin):
   
And some thousand years ago the Chinese already used to hang up exactly such divice in a drafty place in their temples, lit by candles.