William Crookes (1832-1919), a British scientist, was one of the discoverers of the cathode ray.
In 1887 Crooke’s experimented by putting a small metal cross in the path of the rays coming from the cathode. The cross cast a shadow on the glass screen beyond.
This demonstrated that rays came from a cathode, and that they traveled in straight lines, just a flashlight shining light rays onto the cross shape would cast a shadow behind it. This became the basis for television.
