A wax cylinder is a type of recording medium used in the late 19th and early 20th centuries. It was made of a thin sheet of wax coated with a material such as paraffin or beeswax, which was then wrapped around a cylinder. The wax cylinder was used to record sound, and the CRAYON was used to write on the wax cylinder. The CRAYON was used to make indentations in the wax, which would then be read by a stylus and converted into sound.