1897.] Signalling through Space ivithout Wires. 467 



WEEKLY EVENING MEETING, 



Friday, June 4, 1897. 



Sir Fbederick Bramwell, Bart. D.C.L. LL.D. F.R.S. 

 Honorary Secretary and Vice-President, in the Chair. 



W. H. Preece, Esq. C.B. F.R.S. M. Inst. C.E. 



Signalling through Space without Wires. 



Science has conferred one great benefit on mankind. It has sup- 

 plied us with a new sense. We can now see the invisible, hear the 

 inaudible, and feel the intangible. We know that the universe is 

 filled with a homogeneous continuous elastic medium which transmits 

 heat, light, electricity and other forms of energy from one point of 

 space to another without loss. The discovery of the real existence 

 of this " ether " is one of the great scientific events of the Victorian 

 era. Its character and mechanism are not yet known by us. All 

 attempts to " invent " a perfect ether have proved beyond the mental 

 powers of the highest intellects. We can only say with Lord Salis- 

 bury that the ether is the nominative case to the verb " to undulate." 

 We must be content with a knowledge of the fact that it was created 

 in the beginning for the transmission of energy in all its forms, 

 that it transmits these energies in definite waves and with a known 

 velocity, that it is perfect of its kind, but that it still remains as 

 inscrutable as gravity or life itself. 



Any disturbance of the ether must originate with some disturb- 

 ance of matter. An explosion, cyclone or vibratory motion may 

 occur in the photosphere of the sun. A disturbance or wave is im- 

 pressed on the ether. It is propagated in straight lines through 

 space. It falls on Jupiter, Venus, the Earth and every otlier planet 

 met with in its course, and any machine, human or mechanical, 

 capable of responding to its undulations indicates its presence. Thus 

 the eye supplies the sensation of light, the skin is sensitive to heat, 

 the galvanometer indicates electricity, the magnetometer indicates 

 disturbances in the earth's magnetic field. One of the greatest 

 scientific achievements of our generation is the magnificent generali- 

 sation of Clerk-Maxwell that all these disturbances are of precisely 

 the same kind, and that they differ only in degree. Light is an 

 electromagnetic phenomenon, and electricity in its progress through 

 space follows the laws of optics. Hertz proved this experimentally, 

 and few of us who heard it will forget the admirable lecture on 



