546 POPULAR LECTURES AND ADDRESSES. 



comparatively Short Wave-lengths." The paper 

 itself is not long, and I shall read it to you in full, 

 from the Report of the British Association, 1883: 

 " This is by utilising the alternating currents pro- 

 duced when an accumulator is discharged through 

 a small resistance. It is possible to produce waves 

 of as little as 2 metres wave-length, or even less." 

 This was a brilliant and useful suggestion. Hertz, 

 not knowing of it, used the method ; and, making 

 as little as possible of the "accumulator," got 

 waves of as little as 24 cm. wave-length in many 

 of his fundamental experiments. The title alone 

 of Fitzgerald's other paper, " On the Energy Lost 

 by Radiation from Alternating Currents," is in 

 itself a valuable lesson in the electromagnetic 

 theory of light, or the unclulatory theory of mag- 

 netic disturbance. It is interesting to compare it 

 with the title of Hertz's eleventh paper, " Electric 

 Radiation " ; but I cannot refer to this paper with- 

 out expressing the admiration and delight with 

 which I see the words "rectilinear propagation," 

 " polarisation," " reflection," " refraction," appearing 

 in it as subtitles. 



