40 Chevalier G. Marconi [March 3, 



over a distance of 152 miles over land, and will shortly be employed 

 in connection with the new transatlantic stations. 



In conjunction with Professor Fleming, the author has recently 

 introduced further improvements which greatly increase the efficiency 

 of the apparatus, but which he is not at present free to describe. 

 The author here demonstrated the effect of the improvement by 

 means of a galvanometer, showing the deflection without and with 

 the new device. The author also exhibited and explained Dr. 

 Fleming's cymometer for measuring the length of waves used in 

 wireless telegraphy.* 



A very considerable amount of public interest has been centred 

 during the last few years on the tests and experiments in which the 

 author has been engaged in investigating the possibilities of wireless 

 telegraphy over very great distances, and especially on the tests which 

 are being carried out across the Atlantic Ocean. 



The facility with which distances of over 200 miles could be 

 covered with the author's apparatus as long ago as 1900, and the 

 knowledge that by means of syntonic devices mutual interferences 

 could be prevented, led the author to advise the construction of two 

 large power stations, one in Cornwall and the other in North America, 

 in order to test whether, by the employment of much greater power, 

 it might not be possible to transmit messages across the Atlantic Ocean. 



On the erection of these stations very extensive tests and ex- 

 periments were carried out during the latter part of 1902. These 

 tests were greatly facilitated by the courtesy of the Italian Govern- 

 ment, which placed a 7000-ton cruiser, the Carlo Alberto, at the 

 author's disposal. During these trials the interesting fact was 

 observed that, unlike what occurs with moderate power-transmitting 

 stations, the effect of intervening land or mountains between the 

 sending and receiving apparatus does not bring about any consider- 

 aV)le reduction in the distances over which it is possible to com- 

 municate ; this result being due, no doubt, to the much greater 

 length of wave radiated by the big elevated conductor of the long- 

 distance stations, compared with the shorter wave-length radiated by 

 the smaller and less powerful installations. Thus messages were 

 received from Poldhu at the positions marked on the map (Fig. 13), 

 which is a copy of the map accompanying the official report of the 

 experiments. These positions, at which signals were received direct 

 from Poldhu, are in the Baltic near Sweden, at Kiel, the North Sea, 

 the Bay of Biscay, also Ferrol, Cadiz, Gibraltar, Sardinia, and Spezia. 

 Messages were received distinctly in these places from Cornwall, 

 although, in the Baltic, the whole of England, the Netherlands, and 

 part of Germany and Scandinavia lay between Poldhu and the 

 Carlo Alberto. Also, at Cadiz and Gibraltar, the whole of Spain 



• Dr. J. A. Fleming, "On an Instrument for the Measurement of the 

 Length of Long Electric Waves and also Small Inductances and Capacities." 

 Proc. Roy. Soc. Lond., vol. Ixxiv. 



