1908.] 



on Transatlantic Wireless Telegra]ohy. 



109 



in their place unexpected barriers manifested themselves, and my 

 efforts and those of my collaborators have been mainly directed to the 

 solution of problems presented by difficulties which were not antici- 

 pated when the tests over long distances were first initiated. 



In January 1901, wireless communication was established between 

 St. Catherine's Point in the Isle of Wight and Lizard in Cornwall, 

 over a distance of 186 miles. 



The height of these stations above the sea level did not exceed 

 300 feet (100 metres), whereas to clear the curvature of the earth a 

 height of more than a mile at each end would have been necessary. 



The result of these tests went far to convince me that electric 

 waves produced in the manner I had adopted were able to make 

 their way round the curvature of the earth, and that therefore it was 

 not likely that this factor would constitute a barrier to the transmission 



FIC.2 



CHART or THE CNCL I SH CH ANNEIL 



SHOWINC MARCONI WIRELESS, TELEGRAPH STATIONS AT 



H I TON(lSLE or MIGHT) AND THE L I Z ARO 



of waves over greater distances. At this time I had achieved a con- 

 siderable measure of success, by means of syntonic or tuning devices, 

 in preventing mutual interference between stations, and Professor 

 Fleming described, in a letter to the Times dated October 4, 1900, the 

 results obtained, and which he and others had witnessed.* 



The principle on which the transmitters and receivers at St. 

 Catherine's Point and the Lizard were worked is shown in diagrams 

 ?i and 4. 



At the transmitting end a condenser, usually taking the form of a 

 battery of Leyden jars, Imd one terminal connected to one spark-ball 

 of an induction coil or transformer, and the other to the primary 

 circuit of an oscillation transformer. The opposite terminal of this 

 transformer circuit was joined to the second spark-ball. The con- 

 denser was charged to the potential necessary to produce a suitable 



Jouru. Soc. Arts, xlix. No. 2530, 1901. 



