WIRELESS TELEPHONY." 



[\Yitli 20 plates.] 



By R. A. Fessenden.^ 



PREFACE. 



The discussion of the theory, practical operation, and possibilities 

 of wireless telephony is facilitated by first briefly considering the 

 history of the development of wireless signaling generally. 



BRIEF HISTORY OF THE DEVELOPMENT OF WIRELESS SIGNALING. 



Introduction. — In preparing this note it has been considered best, 

 for the sake of accuracy, to refer to published results, such as scientific 

 articles or theses or patent specifications. For the sake of brevity, 

 references to work done in repetition of previously published work 

 have as a rule been omitted. So far as possible, the expression of per- 

 sonal opinion has been avoided in this section of the paper, the object 

 being to gather together in concise form the facts known in regard to 

 the development of the art. With the exception of Munk's original 

 paper, which could not be obtained, all references have been verified 

 by consulting the original publications, a work of some labor, and 

 if any omissions or mistakes have been made, data for their correction 

 will be much appreciated. 



Origin and Development of Old or Damped Wave-coherer Method 



(period 1838-1897). 



Joseph Henry, to whose work the development of wire telegraphy 

 owes so much, was the first (1838-1842) to produce high frequency 



° Copyright, 1908. by A. I. E, E. Reprinted, by permission, from Proceed- 

 ings of the American Institute of Electrical Engineers, Vol. XXVII, No. 7, July, 

 1908, New York. 



'' A paper presented at the Twenty-fifth Annual Convention of the American 

 Institute of Electrical Engineers, Atlantic City, N. J., June 29, 1908. 



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