Probably no scientific discovery has received wider attention than the promulgation of the use of this ray has elicited.
Prof. William Conrad Roentgen attracted the attention of the world when he succeeded in making photographs of the bones of the human body through the living subject. Earlier experimenters had described photographic activity in cathode rays, and it may be proper to consider some of their work.
In 1879 Prof. William Crookes presented to the Royal Society a paper embodying the results of a series of remarkable experiments on electrical discharges through vacua. Previous to this, experimenters had investigated discharges through rarefied gases, and had observed in a general way the behavior of discharges in comparatively high vacua. Faraday also had speculated on the possibility of an attenuated state of matter in which the behavior of molecules might be expected to be different than in the case of matter in any