1897.] on the Polarisation of the Electric Bay. 307 



polariser is one's outstretched fingers. I interpose my fingers at 45° 

 between the crossed polariser and the analyser, and you observe the 

 immediate restoration of the extinguished field of radiation. The 

 double-conducting nature of the structure is here quite evident. 



While repeating these experiments I happened to have by me this 

 old copy of ' Bradshaw,' and it struck me that here v^^as an excellent 

 double-conducting structure which ought to polarise the electric ray. 

 For looking at the edge of the book we see the paper continuous in 

 one direction along the pages, whereas this continuity is broken across 

 the pages by the interposed air-films. I shall now demonstrate the 

 extraordinary efiiciency of this book as an electric polariser. I hold 

 it at 45° between the crossed gratings, and you observe the strong 

 depolarisation effect produced. I now arrange the polariser and the 

 analyser in a parallel position, and interpose the ' Bradshaw ' with 

 its edge parallel to the electric vibration ; there is not the slightest 

 action in the receiver, the book held in this particular direction being 

 perfectly opaque to electric radiation. But on turning it round 

 through 90°, the ' Bradshaw,' usually so opaque, becomes quite trans- 

 parent, as is indicated by the violent deflection of the galvanometer- 

 spot of light. An ordinary book is thus seen to act as a perfect 

 polariser of the electric ray ; the vibrations parallel to the pages are 

 completely absorbed, and those at right angles transmitted in a 

 perfectly polarised condition. 



The electric radiation is thus seen to be reflected, refracted and 

 polarised just in the same way as light is reflected, refracted and 

 polarised. The two phenomena are identical. The anticipations of 

 Maxwell have thus been verified by the great work of Hertz and his 

 successors. 



By pressing the key of this radiation apparatus I am able to pro- 

 duce ether vibrations, 30,000 millions in one second. A second stop 

 in connection with another apparatus will give rise to a diflerent 

 vibration. Imagine a large electric organ provided with a very large 

 number of stops, each key giving rise to a particular ether note. 

 Imagine the lowest key producing one vibration in a second. W& 

 should then get a gigantic ether wave 186,000 miles long, Let the 

 next key give rise to two vibrations in a second, and let each succeed- 

 ing key produce higher and higher notes. Imagine an unseen hand 

 pressing the different keys in rapid succession. The ether notes will 

 thus rise in frequency from one vibration in a second, to tens, to 

 hundreds, to thousands, to hundreds of thousands, to millions, to 

 millions of millions. While the ethereal sea in which we are all 

 immersed is being thus agitated by these multitudinous waves, we 

 shall remain entirely unaffected, for we possess no organs of percep- 

 tion to respond to these waves. As the ether note rises still higher 

 in pitch, we shall for a brief moment perceive a sensation of warmth. 

 As the note still rises higher, our eye will begin to be affected, a red 

 glimmer of light will be the first to make its appearance. From 

 this point the few colours we see are comprised within a single octave 



