38 



Chevalier G. Marconi 



[March 3, 



of its application for over two years to commercial purposes, the 

 author is able to say that, in so far as concerns speed of working, 

 faciUty of adjustment, reliability and efficiency when used on tuned 

 circuits, this receiver has left all coherers or anti-coherers far 

 behind. 



The action of this receiver is in the author's opinion based upon 

 the decrease of magnetic hysteresis which takes place in iron, when 

 under certain conditions this metal is exposed to high frequency 

 oscillations or Hertzian waves. 



It is constructed in the following manner and is shown in Fig. 12. 



On an insulating sleeve surrounding a portion of a core, consisting 

 of an endless rope of thin iron wires, are wound one or two layers of 

 thin insulated copper wires. Over this winding insulating material 

 is placed, and over this again another longer winding of thin copper 

 wire contained in a narrow bobbin. The ends of the windings nearer 

 the iron core are connected one to earth and the other to the elevated 



Fig. 12. 



conductor, or they may be joined to any suitable syntonising circuit, 

 such as is now employed for syntonic wireless telegraphy. The ends 

 of the longer winding are connected to the terminals of a suitable 

 telephone. A pair ojp horse-shoe magnets are conveniently disposed 

 for magnetising the portion of the core surrounded by the windings, 

 and the endless iron core is caused to move continuously through the 

 windings and the field of the horse-shoe magnets. 



This detector is and has been successfully employed for both long 

 and short distance work. It is used on the ships of the Royal Navy 

 and on all transatlantic liners which are carrying on a long-distance 

 news service. It has also been used to a large extent in the tests 

 across the Atlantic Ocean. 



As already stated, the adoption of this magnetic receiver was the 

 means of bringing about a great improvement in the practical work- 

 ing conditions of wireless telegraphy, by making it possible to do away 

 with the troublesome adjustments necessary when using coherers, and 

 also by considerably increasing the speed at which it is possible to 



