MAGNETISM, ELECTRICITY, LIGHT, HEAT, AND MOTION 117 



Fig. 23. — Diagi-am of telephone (after Trowbiidge). 



we call light. According to this theory, the displacements of the ether will produce a disturbance of the vortices, 

 and this disturbance of the vortices can be supposed to react on the ether, and in this way can affect the pro- 

 pagation of Ught." ^ 



If a Leyden jar be discharged through a great circle of wire placed in one room, electro-magnetic waves can be 

 sent through brick walls and detected in another room by the sparks excited in a similar circle of wire connected 

 with a second Leyden jar. The electro-magnetic waves undulate in the direction of their length ; they also 

 undulate athwart the path of the wave's advance. " The ether, though homogeneous and continuous, may be, as 

 regards its density, rendered heterogeneous by motion (' Hypotheses of Vortex Molecules,' by Lord Kelvin). Magnetic 

 influence on light indicates a rotational motion of the media when magnetised. This motion does not imply a 

 dissipation of energy." No substance cuts of! the lines of magnetic force : they pass through wood, stone walls, 

 copper, and all metals. Ether transmits transverse vibrations to very great distances without sensible loss of 

 energy. Ordinary atmospheric air can transmit waves of sound which move to and fro in the direction in which 

 they are propagated. It cannot, however, transmit waves of heat, Ught, and electricity, which require transverse 

 vibrations and the presence of ether. A good illustration of heat and Ught waves is obtained by throwing a 

 stone into a placid pool of water. The waves spread in ever-widening circles fi'om the centre of disturbance, and 

 indicate the direction of progress. They have also a vertical movement at right angles (transverse in character) 

 in addition to the spreading movement. 



As there is no limit to space, and ether (or its equivalent) occupies all space, electrical and other movements 

 are propagated to all parts of the universe, and hence the possibihty 

 of wireless telegraphy, which is mainly due to molecular vibrations and 

 pulsations of the ether in space. The same is true of the telephone, 

 where the ■'nbrations are originally produced by the vocal chords 

 (human voice) or other sounding bodies. The vibrations are, in the 

 first instance, conveyed to a thin vibrating disc, which, having to-and- 

 fro movements communicated to it, causes the molecules in space to 

 react upon each other in waves to a practically unUmited extent. The 

 vibrations generated in one locahty can be collected by a duplicate 

 vibrating disc in another, with the result that messages can be trans- 

 mitted incredibly long distances.^ This extraordinary achievement is only possible when there is unhmited matter 

 and motion : any breach of continuity either in the matter or the motion would be fatal to the principle and 

 practice of wireless telegraphy and telephony. The telephone, a sketch plan of which is appended (Fig. 23), is 

 an instrument based entirely on Faraday's discovery of magnetic induction. It was discovered by Professor 

 Graham Bell, who has acquired a great reputation as an authority in the physics of sound. 



The electric telegraph (discovered before the telephone by Morse and others) acts on essentially the same 

 principle as the telephone. Both transmit messages by means of electro-magnets and insulated wires ; the earth 

 in certain cases acting as a return wire. Dynamo machines, electro-magnets, and insulated wires perform the 

 bulk of electric work. Electricity, Hke heat and Ught, as already indicated, is regarded as a form of motion ; 

 the only difference between electricity, heat, and Ught consisting in the length of the waves. The waves of heat, 

 for example, approximate to those of electricity, and are longer than those of Ught. " AU space is fiUed with 

 a medium which transmits electro-magnetic waves to us from the sun." The sun, which is the source of the 

 electro-magnetic waves, has been compared to an enormous electrical furnace, consisting of a mass of molten metals 

 where carbon is freed from its impurities, and the metals driven off in vapour. The presence of oxygen in the sun 

 seems necessary to account for the exceeding splendour and brilliancy of that magnificent orb. Faraday and Dewar 

 have shown that oxygen is strongly magnetic.^ 



" We have already strong grounds for believing that we hve in a medium which conveys to-and-fro or periodic 

 movements to us from the sun, that these movements are electro-magnetic, and that all the transformations of Ught 



' Trowbridge, op. cit. pp. 264, 265, 272 and 273. 



^ As to the distance which may be covered by wireless telegraphy the annexed report by Signer Marconi's assistant in the Scvlsiiian of 

 March 12, 1907 is at once instructive and impressive : — "Nine years have passed since the writer became assistant to M. Marconi at the first 

 raodei-n wireless telegraph station. The distance over which messages were transmitted was not great, only about 14 miles, but the transmission 

 was regular, if slow, and suffered but little from interruptions. Previous wireless systems, such as those of Morse, Lindsay, Willoughby-Sniith, 

 Stevenson, and Preece, had been based on different principles, and had never attained to distances above a very few miles. Great distance is now 

 a matter of so little notice that few people are even aware that there are at least a dozen wireless stations in different parts of the world which 

 maintain regular telegraphic communication with others which are over a thousand miles off. The Atlantic Ocean is 3000 miles wide, but 

 the gi-eat Cunarders are never out of direct touch with either England or America. Panama is connected directly with Manhattan Beach, 2170 

 miles distant, and recent results show that Boston, though 3000 miles off, will be veiy shortly in permanent conmmnication witli Machrihanish, 

 in Kintyre." 



' Oxygen is said to constitute the largest portion of the solid and liquid substances of our planet so far as we know it ; and nitrogen is 

 by far the predominant constituent of our atmosphere. 



