262 



THE WORLD'S ADVANCE 



meters and the arfc will consume about 

 100 K. W. of energy. 



Another large transmitting station em- 

 ploying undamped oscillations has been 

 erected by the Universal Radio Syndi- 

 cate at New Castle, New Brunswick, 

 Canada. This station is now in opera- 

 tion and is fitted with a Poulsen arc 

 type of transmitter. It has not been 

 definitely discerned with whom this sta- 

 tion communicates, but it may be heard 

 at certain intervals in the United States, 

 testing. This station was designed with 

 the idea of carrying on correspondence 

 with the similar station located at Ports- 

 mouth, England. Such communication, 

 however, has not been established. 



Another highly successful long dis- 

 tance radio circuit is that of the Mar- 

 coni Company between Bolinas and Mar- 

 shalls, Cal., and Kahuku and Koko Head, 

 Hawaii. These stations employ the ro- 

 tary disc type of spark discharger giving 

 feebly damped oscillations and a very 

 clear musical note. The service ren- 

 dered between these two points has been 

 very satisfactory, so much so that the 

 cables were compelled to reduce their 

 rates in order to meet the competition. 

 Owing to the fact that the transmitting 

 and receiving stations on the Pacific 

 coast and at Hawaii are separated by a 

 number of miles, it is possible to carry 

 on communication both ways simultan- 

 eously. In fact, this is the great feature 

 of the Marconi long distance systems 

 not yet attained by others. By this 

 method they are not only enabled to han- 



dle traffic in both directions, but the 

 operators also may break each other and 

 request the instant repetition of a word 

 or sentence. 



Signalling is carried on between these 

 stations at any speed desired, and it is 

 proposed at a later period to operate 

 them at a speed of 75 words per minute. 



It may be interesting to the reader to 

 know that the high potential circuits 

 from the secondary of the transformer at 

 these stations is interrupted by means of 

 a specially designed high potential relay 

 in turn operated by a smaller key. In 

 fact, it is of interest to sum up the 

 methods by which the signalling in these 

 large stations is effected, viz.: (i) in the 

 case of the spark stations, the high poten- 

 tial circuit from the secondary winding 

 of the transformer to the condenser is 

 interrupted by a specially designed high 

 potential electro-magnetic break fitted 

 with air blasts; (2) in the arc stations a 

 . portion of the aerial tuning inductance is 

 shunted by a telegraph key, thereby 

 changing the emitted wave length; (3) 

 in the high-frequency alternator systems, 

 the D. C. circuit to the field coils is gen- 

 erally interrupted by a telegraph key. 



The universal use of arc stations is 

 apt to cause a conglomeration of radio 

 traffic for the reason that these sets emit 

 two wave lengths, one of which is 

 radiated when the transmitting key is 

 up, and the second wave length when it 

 is depressed, thus doubling the interfer- 

 ence produced by the ordinary spark for 

 generator stations. This may become a 



ffllt is now a matter of history that the first "long distance" 

 jlattempts at wireless communication took place on March 

 27th, 1899, when Marconi succeeded in sending messages be- 

 tween the station at Wimereux, near Boulogne, France, and 

 another at the South Foreland Lighthouse, on the Goodwin 

 Sands, England. The total distance traveled by the signals was 

 about thirty-two miles, and so remarkable was the feat consid- 

 ered that newspaper men from almost every nation were pres- 

 ent to witness the tests. A ten-inch spark coil was employed 

 to transmit the signals, which were detected by a coherer and 

 recorded on a paper ribbon by means of a Morse register. 



