Photo: Ernest ft. Mills. 



SIR WILLIAM CROOKES 



Sir William Crookes experimented on the electric discharge in 

 vacuum tubes and described the phenomena as a "fourth state of 

 matter." He was actually observing the flight of electrons, but he 

 did not fully appreciate the nature of his experiments. 



Photo: l'h<ii'. 



PROFESSOR SIR \v. H. Hk\<i(; 

 One of the mott distinguished physicists of the present day. 



