114 Gommendatore G. Marconi [March 13, 



conducting tests across the Bristol Channel for the Post Office in 

 1897.* 



It will be understood, however, that when it came to flying a kite 

 on the coast of Newfoundland in the month of December, this method 

 was neither an easy nor a comfortable one. When the kites were got 

 up much difficulty was caused by the variations of the wind producing 

 constant changes in the angle and altitude of the wire, thereby causing 

 corresponding variations in its electrical capacity and period of elec- 

 trical resonance. My assistants at Poldhu, in Cornwall, had received 

 instructions to send on and after December 11, during certain hours 

 every day, a succession of S's followed by a short message, the whole 

 to be transmitted, at a certain pre-arranged speed, every ten minutes, 

 alternating with five minutes' rest. 



Owing to the constant variations in the capacity of the aerial 

 wire in Newfoundland, it was soon discovered that an ordinary syn- 

 tonic receiver was not suitable, although, at one time, a number of 

 doubtful signals were recorded. I therefore tried various microphonic 

 self -restoring coherers placed either directly in the aeri.d or included 

 in the secondary circuit of an oscillation transformer, the signals 

 being read on a telephone. 



On December 12 the signals transmitted from Cornwall were 

 clearly received, at the pre-arranged times, in many cases a succession 

 of S's being heard distinctly, although probably in consequence of 

 the weakness of the signals and the constant variations in the height 

 of the receiving aerial no actual message could be deciphered. 



The following day we were able to confirm the result. The 

 signals were actually read by myself and by my assistant, Mr. G. S. 

 Kemp. 



I have often been asked why I adhered to the practice of trans- 

 mitting series of the letter S for these tests. The reason is that the 

 switching arrangements at the sending station at Poldhu were not 

 constructed at that time in such a manner as to withstand long periods 

 of operation — especially if letters containing dashes were sent — with- 

 out considerable wear and tear, and that if S's were sent, an automatic 

 sender could be employed. Moreover, the immediate object of these 

 experiments was not to transmit actual messages across the ocean, 

 but to ascertain the possibility of detecting the effects of electric 

 waves at a distance of 2000 miles. 



The result obtained, although achieved with imperfect apparatus, 

 was sufficient to convince me and my co-workers that by means of 

 permanent stations (that is, stations not dependent on kites or 

 balloons for sustaining the elevated conductor) and by the employ- 

 ment of more power in the transmitters it w^ould be possible to send 

 Qiessages across the Atlantic Ocean with the same facility with which 

 ihey were being sent over much shorter distances. 



* ' Signalling through Space without Wires,' lecture by Sir William 

 Preece, Royal Institution, June 4, 1897. Proc. R.I. xv. p._467. 



