The Collaborative International Dictionary
Crookes tube \Crookes" tube`\ (kr??ks" t?b`). (Phys.) A vacuum tube in which the exhaustion is carried to a very high degree, with the production of a distinct class of effects; -- so called from W. Crookes who introduced it.
Wikipedia
A Crookes tube is an early experimental electrical discharge tube, with partial vacuum, invented by English physicist William Crookes and others around 1869-1875, in which cathode rays, streams of electrons, were discovered.
Developed from the earlier Geissler tube, the Crookes tube consists of a partially evacuated glass container of various shapes, with two metal electrodes, the cathode and the anode, one at either end. When a high voltage is applied between the electrodes, cathode rays ( electrons) are projected in straight lines from the cathode. It was used by Crookes, Johann Hittorf, Julius Plücker, Eugen Goldstein, Heinrich Hertz, Philipp Lenard and others to discover the properties of cathode rays, culminating in J.J. Thomson's 1897 identification of cathode rays as negatively charged particles, which were later named electrons. Crookes tubes are now used only for demonstrating cathode rays.
Wilhelm Röntgen discovered X-rays using the Crookes tube in 1895. The term is also used for the first generation, cold cathode X-ray tubes, which evolved from the experimental Crookes tubes and were used until about 1920.
Usage examples of "crookes tube".
Recognising the bubbling evil as no substance reach able by matter or material chemistry, and therefore ignoring the flame-thrower which loomed on my left, I threw on the current of the Crookes tube apparatus, and focussed toward that scene of immortal blasphemousness the strongest ether radiations which men's art can arouse from the spaces and fluids of nature.
His visit was merely for the purpose of gathering some apparatus, which included a Crookes tube, carefully packed, a rheostat, and some other paraphernalia which we divided.
Across the dim room flashed a pale blue light with a crackling noise, the visible rays from a Crookes tube, I verily believe.