24 REPORT 1891. 



penetrates between the molecules of all ordinary matter, and 

 acts as the transmitter of motion and energy from one body to 

 another. 



Professor Fitzgerald has shown that if the ether be sup- 

 posed a perfect fluid in turbulent motion made up of columnar 

 vortices interlaced with one another, and having their axes at 

 all possible angles, and the atoms of ordinary matter free 

 vortices threading between these interlaced ones, all the 

 phenomena of nature could be explained as due to different 

 movements in space. 



Sir W. Thomson has proved that aperfect liquid in motion of 

 this kind is in a stable state of motion. On this theory, then, 

 atoms of matter would be the free vortex-rings. Electricity 

 would be the interlaced vortices : positive, those that rotate 

 in one direction ; negative, those that rotate in the other. 

 Magnetism would be a displacement of the interlaced vortices, 

 thus reversing the usual theory that electricity is a displace- 

 ment or flow, and magnetism a twist or whirl. The fact that 

 magnetism causes a rotation of the plane of polarisation of 

 light and other rotatory phenomena is no objection to Fitz- 

 gerald's theory, for there is no reason why a direct flow should 

 not cause a rotation, as any one will see on considering the 

 case of an ordinary water-wheel. 



The theory that light is an electrical phenomenon we owe to 

 Maxwell. It was his greatest discovery, and is without doubt 

 one of the greatest of this century. Since he stated it in 1865 

 confirming evidence has been accumulating on all sides, and 

 now it may be considered as completely verified. 



The main proof of the theory is that both light and electric 

 disturbance or radiation are propagated through the ether by 

 the same kind of motion, and that both disturbances travel 

 with exactly the same velocity. 



We know that light is due to a periodic vibration which is 

 communicated across the ether by a particular kind of wave- 

 motion. It has long been known that the discharge of a 

 Leyden jar is not a single rush in one direction, but a series 

 of rushes of the electricity oscillating backwards and forwards 

 between the coatings, and having a definite period which 

 depends on the capacity and the inductance of the jar. The 

 oscillations gradually become smaller as the enei'gy of the 

 charge is frittered away in heat, but while they last they 

 send out electric waves through the surrounding medium, 

 just as an incandescent molecule sends out light-waves. If now 

 another jar exactly similar to the first, so that its period of 

 oscillation is the same, be placed in the neighbourhood, the 

 oscillations of the former, communicated through the intervening 

 space as ether-waves, will be taken up by the latter, exactly 

 as one tuning-fork will vibrate in sympathetic resonance with 



