Stewart. — Address. 9 



clue the form of coherer which appears to be the most sensi- 

 tive and practical method of catching vibrations in the ether 

 set in motion by powerful sparks discharged it may be a 

 hundred miles distant. 



The question now arises, To what extent, from a com- 

 mercial point of view, is wireless telegraphy likely to come 

 into use? Gushing writers, in crowding together the coming 

 achievements of the century, take for granted that all wires, 

 alike for telegraph and telephone, will be abolished. Granted 

 that perfection is reached in practice, and that it is possible 

 to dispense with telephone-wires between any two instru- 

 ments, it will be readily admitted that a system by which a 

 receiver could respond to and translate into speech all or 

 any of the efcheric vibrations set up by thousands of instru- 

 ments would be of no value, to say the least of it. Hence 

 Marconi endeavoured to devise means by which the vibrations 

 could be reflected, or, at all events, very much strengthened, 

 in a given direction. But it is hard to conceive Hertzian 

 waves, which are supposed to be able to pass through stone 

 walls, being reflected by anything. This reflection idea, 

 therefore, has not been much in evidence of late. But it is 

 asserted that a receiver may be tuned so as to syntonize 

 with a particular transmitter, and that signals would be in- 

 telligible only between these two. Granted again, what 

 follows in practice ? Each subscriber must be supplied with 

 instruments tuned to those of every other member of the 

 Exchange. This, of course, is unthinkable, and therefore for 

 telephony wires cannot be superseded. For telegraphy it 

 might be possible to use a cryptograph, by which messages 

 might be deciphered only by those holding the key. It may 

 be objected that all ciphers are solvable by scientific methods, 

 but there is one very simple instrument, known as the Wheat- 

 stone Cryptograph, which is absolutely unsolvable without 

 the key, and that key may be varied through millions of 

 commutations. 



It is thus more than doubtful if wireless telegraphy may 

 become commercially useful. But there is a large and very 

 important field of usefulness otherwise open. At sea espe- 

 cially, both in peace and war, it must become of immense 

 importance. We all remember the long search that took place 

 some time ago after two disabled steamers. Had they, and 

 also those engaged in the search, been supplied with Marconi's 

 instruments, the work would have extended to days instead 

 of weeks or months, and been one of system instead of 

 chance. So, also, for enabling an admiral to communicate 

 with his fleet during foggy weather, or with detached ships or 

 squadrons, and for lighthouses and lightships communicating 

 with shore stations, the invention appears to be perfect. It 



