1908.] 



on Transatlantic Wireless Telegra^jhy. 



117 



Contemporaneouslv with the construction of the station at Glace 

 Bay, alterations and modifications were executed at Poldhu. Four 

 wooden lattice towers, each 210 feet high, were erected at the corners 

 of a square of 200 feet side. The towers carried insulated triatic 

 stays from which was suspended a conical arrangement of four hundred 

 copper wires forming the aerial, put up in sections so that more or 

 less could be employed (Fig. 8). The buildings for the generating 

 plant were placed in the middle of the space between the towers. 

 Additional machinery was obtained, and alterations carried out in 

 accordance with the experience obtained from previous tests. 



Identical towers and aerial arrangements were at that time 

 adopted at the stations at Glace Bay, and at the similar installation 

 in course of erection at Cape Cod, Mass. 



F'^S 



In most of the experiments carried on from Poldhu the capacity 

 of the sending condenser was -^Vth of a microfarad, the spark length 

 1 j inch, and the wave-length 3600 feet. In these and subsequent 

 tests the double condenser arrangement of Dr. Fleming was replaced 

 by a single condenser, the arrangement being similar to that shown 

 in Fig. 8. 



During the time that constructional work was in progress at 

 Glace Bay, I carried out some tests with Poldhu over considerable 

 distances, and these tests were greatly facilitated by the interest taken 

 in them by the Italian Government, w^hich placed the cruiser Carlo 

 Alberto at my disposal. 



During these experiments the interesting fact was observed that, 

 when using waves of over 1000 metres in length, intervening land or 



