The Danger of Hertzian Waves 



By B. S. Blakee 



THE discharge of an electric spark is 

 the source of radiant energy cap- 

 able of producing at a distance upon 

 an electrical apparatus called a "reson- 

 ator" powerful vibratory movements 

 which are liable to give rise to other 

 sparks. This phenomenon was first ob- 

 served by the German physician Hertz, 

 by means of a metallic circle cut in such 

 a way as to leave the free ends close 

 together, placed in an oscillating field of 

 induction. This principle has been made 

 use of recently in England to cause an 

 explosion in the hull of an old ship lying 

 at some distance from a wireless sta- 

 tion. The details of the operation have 

 been kept secret, but a similar experi- 

 ment may be made with the following 

 simple apparatus: 



Fill a glass flask with an explosive 

 mixture of oxygen and hydrogen (two 

 volumes of H to one of O) and close 

 the mouth of the flask with a stopper 

 of paraffin through which have been 

 pushed two steel needles with blunt 

 and polished points, so that they ap- 

 proach at an angle and leave a small 

 space between the ends. Now connect 

 the needles to long insulated wires, 

 which may be extended to the earth 

 or hung on brackets in opposite direc- 

 tions. If operated in stormy weather, 

 or in the neighborhood of a wireless, 

 station, one will not have to wait long 

 for a spark induced by an electric 

 wave, which will cause the explosion 

 of the gases with a report like the 

 crack of a pistol. 



This experiment of the English Ad- 

 miralty is probably the first in which 

 these waves have been voluntarily 

 used to cause destruction, but it is not 

 certain that the destroyed ship is the 

 first victim of electric resonance. 



The accidental occurrence of the 

 Hertzian experiment is perhaps more 

 common than is imagined, on account 

 of the numerous resonators which 



chance leaves in the paths of the elec- 

 tric waves. It is only necessary that 

 such conditions be present in an in- 

 flammable medium to cause a fire. 



M. Duroquier, writing in La Nature, 

 says that he would be sorry to cause 

 unnecessary alarm to sailors, miners 

 and aeronauts, but the memory of re- 

 cent catastrophes in which many lives 

 have been lost leads one to believe that 

 special care should be taken under cer- 

 tain conditions and in certain localities 

 to counteract the effects of the electric 

 waves which reach to the depths of a 

 mine as readily as they reach a ship at 

 sea or a dirigible balloon in the air. 



On board ship some chain, or per- 

 haps scrap iron in the coal bunkers may 

 cause sparks which will start a fire. 

 In the case of a battleship, shells lying 

 close together in a badly ventilated 

 ammunition vault may be exploded by 

 the same means. To cause the firing 

 of a dirigible, all that is necessary is 

 the formation of sparks across some 

 gap in the metallic frame-work. 



Numerous instances may be cited of 

 the inductive effects of these waves. 

 At the wireless post at Mont-Valerien, 

 several miles from Paris, the emissions 

 from the Eiffel Tower give rise, by 

 resonance, to sparks several milli- 

 meters in length at the point of the de- 

 tectors on the receiving table. On 

 shipboard, also, this effect can be ob- 

 served in the metallic rigging when the 

 wireless is in operation. 



Continuing, M. Duroquier says that 

 the dangerous effects of induction are 

 to be feared not only under a storm 

 cloud, or near a radio-telegraphic sta- 

 tion, but especially at points halfway 

 between two powerful stations. He 

 noticed that at his own wireless station 

 some of the delicate instruments were 

 frequently out of order from some un- 

 known cause and by drawing a straight 

 line on a map from Paris to the nearest 

 wireless station, situated at Rochefort, he 



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