New York Times, January 12, 1908, page C2:

VOICE  WILL  CARRY  ACROSS  THE  SEA
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Easily  Borne  on  the  Poulsen  Wireless  Waves,  Declares  the  Inventor.
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TELLS  OF  250-MILE  TEST
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Loss  of  Power  by  His  Undamped  Waves  Less  Than  in  the  Sparkling  Waves  of  Wireless  Telegraphy.
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Special  Correspondence  THE  NEW  YORK  TIMES.

    COPENHAGEN, Dec. 22.--The wonderful achievement of Valdemar Poulsen, chronicled in the newspapers of the world a few days ago, of carrying on a conversation by wireless telephony between Lyngby and Weisensee was the result of years of experimental work. Mr. Poulsen, assisted by a staff of Danish engineers, has been at work for a long time in undertaking to make telephoning by means of his undamped and continuous waves practicable and useful in commercial transactions.
    When Mr. Poulsen had about finished his work with the wireless telegraph he had become convinced that the transmission of oral human speech through the air was possible and at great distances, if he could construct an apparatus for transmission and recording sufficiently strong and powerful. He began experimenting at once at his wireless station at Lyngby, five miles from Copenhagen, and demonstrated that wireless telephoning could be carried, on over considerable distances without losing anything in clearness and distinctness. Having made this demonstration, Mr. Poulsen undertook to improve his apparatus, and almost every day increased the length of the line over which he held conversations with his assistants.
    Finally, last week he had come to have so much confidence in his system that he undertook the risk of trying to speak over a distance of 250 English miles--that being the distance from Lyngby to Weisensee, near Berlin. When Mr. Poulsen at his station at Lyngby clearly heard the voices of his assistants and understood distinctly all that they were saying to him from their station at Weisensee, he was overjoyed. There was a perfect exchange of conversation between the two stations.
    The difference between the sparkling wireless waves and Mr. Poulsen's undamped wireless waves accounts for the great result which Mr. Poulsen has achieved. Mr. Poulsen himself defines the difference as follows:
    "The wireless sparks are to be compared to the shell from a big gun. When fired, you get an enormous blow, like that caused by an explosion, but the force of this blow is lost after a short time. The undamped waves produce a sort of singing vibration of enormous rapidity, and they go on their way around the globe with the same force as that with which they leave the transmitting apparatus.
    "Nothing can stop them, not even the highest mountain. They cannot go through the mountain, but they go singing over it, and then pass along until they reach the receiving apparatus to which they are appointed.
    "It will be easier for the waves to cross the Atlantic, and of course the North Sea, than to go from Weisensee to Lyngby. The station at Lyngby is unfortunately situated for wireless telephonic conversation, especially with the station at Weisensee, which also is badly situated and equipped."
    Valdemar Poulsen, who only 38 years old, is the son of a Judge in the High Criminal Court of Copenhagen. He is a very modest man and has not as yet developed any business in his telephonic work. He is a singularly silent man, but when any one expresses an interest in his work he is willing to explain it to him to the best of his ability and with a never failing enthusiasm.