1902.] on the Progress of Electric Space Telegraphy. 201 



vertical wire a number of corresponding receivers. Different messages 

 can be sent by each transmitter connected to the same radiating wire 

 simultaneously and received equally simultaneously by the vertical 

 wire connected to differently tuned receivers. This result, which I 

 believe was quite novel at the time, I showed to several friends of 

 mine, including Dr. J. A. Fleming, F.R.S., nearly two years ago. 

 Dr. Fleming made mention of the results he had seen in a letter to 

 the London Times dated October 4, 1900. I have further noticed 

 tliat the tuning can be further improved by the combination of the 

 two systems described. In this case the cylinders are connected to 

 the secondary of the transmitting transformer, and the receiver to a 

 properly-tuned induction coil, and all circuits must be tuned to the 

 same period as already described. This arrangement is going to be 

 further tested in long-distance experiments shortly to be undertaken 

 between England and Canada. 



The syntonic systems have not been applied generally to ships, as 

 it has always been considered an advantage that each ship should be 

 able, especially in case of distress, to call up any other ship or ships 

 which may happen to be at the time within the range of its trans- 

 mitter, but in the case of land stations the syntonic method has been 

 applied in several instances where necessity demanded it. Thus at the 

 testing stations which maintain communication bet ween St. Catherine's, 

 Isle of Wight, and Poole, in Dorset, when electric waves of a certain 

 frequency are used, no interference whatever can be caused by the 

 working of the Admiralty installations in the vicinity. The long- 

 distance station at Poldhu, Cornwall, is able to transmit signals 

 decipherable on a tuned receiver on a ship at over 1000 miles dis- 

 tance, while the Lloyd's wireless station at the Lizard, only 7 miles 

 away, is not affected by the powerful waves radiated from Poldhu if 

 tuned to a different frequency. 



I am not at all prepared to say that under no possible circumstances 

 could a wireless message transmitted between syntonic instruments 

 be tapped or interfered with, but I wish to point out that it is now 

 possible to work a considerable number of wireless telegraph stations 

 simultaneously in the vicinity of each other without the messages 

 suffering from any interference. Of course, if a powerful transmitter, 

 giving off waves of different frequencies, is actuated near one of the 

 receiving stations it may prevent the reception of messages, but the 

 ordinary systems of communication through wires may be likewise 

 affected. Prof. 0. J. Lodge, in a report of his experiments in mag- 

 netic space telegraphy, mentions that he was able to interfere with 

 the working of the ordinary wire telephone system in the city of 

 Liverpool. Sir W. H. Preece has also published results which go to 

 show that it is possible to pick up at a distance on another circuit 

 the conversation which may be passing through a telephone wire. 

 About two years ago, at Cape Town, it was found impossible to work 

 the cables landing there during certain hours when the electric 

 tramways of the town were running, and the matter became subse- 



