WEDNESDAY, NOVEMBER 28rd, 1898. 



®£k0rapljg, luitb anir toitbcut Wiixts, 



BY 



Dr. J. A. FLEMING, F.R.S., &c. 



BEFORE proceeding to the more sensational division of his 

 subject, the Professor began by a little exposition of the 

 method of telegraphing with wires, " and," he wisely observed, 

 " I shall not venture to assume that those whom I address are 

 experts in this matter." Next year, in the little town of Como, 

 where he was born, will be celebrated the centenary of the dis- 

 covery of the electric current by Volta, the wizard who dwelt at 

 Pavia. A photograph of the present statue of Volta at Como 

 was thrown upon the sheet, and due honour was done to the 

 great names of Ampere, Joseph Henry, and Sturgeon. In 

 shadow pantomime, through the medium of a powerful lantern, 

 the phenomena of electro-magnetism were exhibited, — the phe- 

 nomena upon which the whole apparatus used in the most elabo- 

 rate telegraphy is founded. It is to Ersted that the credit belongs 

 of finding out the fact which enabled these phenomena to be 

 utilised. He it was who first noticed that the direction of a mag- 

 netic needle enclosed in an electric circuit is reversed by the re- 

 versal of the direction of the current. With the possibility of 

 transmitting to a distance by means of the electric current these 

 opposite indications of the needle. Dr. Fleming explained that 

 the foundation of telegraphic communication was laid, because 

 whenever you have two signs which are able to be repeated in 

 varying alternation, you have the possibility of making a code. 

 The whole operation of sending a telegraphic message in its ele- 

 mentary form was here shadowed on the screen. No one person, 

 said the Doctor, could claim to have been the inventor of the 

 telegraph, but it was first put into practical form in England by 

 Wheatstone and Cook, who invented the " five-needle telegraph," 

 i.i'., and instrument wherein the cumbrous code which had at 

 first to be employed was simplified by the use as indicators of 

 five separately controlled magnetic needles. 



Then were dealt with the later elaborations of the " wire," — 

 the discovery of the fact that if a wire along which a current 

 was to run were carried downward to the earth, the earth itself 



