RECENT ADVANCES IN WIRELESS TELEGRAPHY. 189 



limited to the rate at which the operator could read by sound. So 

 for as speed is concerned, however, this new detector is not dependent 

 upon the ability of the operator. It is possible to use an automatic 

 transmitter to send messages at the rate of 100 words a minute, and 

 the messages will be picked up and recorded quite clearly and dis- 

 tinctly by means of this new form of receiver. 



The author here gave a demonstration of wireless transmission 

 and reception by means of high speed '* Wheatstone " instruments 

 lent by the General Post-OfRce, used in conjunction with his mag- 

 netic receiver. 



This form of recording receiver has been satisfactorily worked 

 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 Doctor Flem- 

 ing's cymometer for measuring the length of waves used in wireless 

 telegraphy.'* 



A very considerable amount of public interest has been centered 

 during the last few yenvs 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 cov- 

 ered with the author's ai^paratus as long ago as 1900, and the knowl- 

 edge 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 Xorth 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 ver}^ extensive tests and experi- 

 ments were carried out during the latter part of 1902. These tests 

 were greatly facilitated by the courtesy of the Italian Government, 

 Avhicli placed a T.OOO-ton cruiser, the Carlo AlJjerto, 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 considerable reduc- 



o- 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. 

 Loud., Vol. LXXIV. 



