San Francisco Call, October 4, 1899, page 4:
ON BOARD STEAMER GRANDE DUCHESSE
NEW YORK, Oct. 3.--Every bulletin sent by Signor Marconi from the steamship Ponce by his wireless system of telegraphy was alphabetically spelled on a receiver in the captain's cabin of the Grande Duchesse. W. J. Clarke, general manager of the United States Electrical Supply Company of this city, was in charge and directed the sending and receiving of messages.
Far from the Ponce, near another part of the great ocean racecourse, the key on the Grande Duchesse worked in perfect sympathy with that under the hands of Signor Marconi's experts. The transmitter was a specially designed transformer, by which Mr. Clarke also converted the light current of a small storage battery into a current of hundreds of thousands of volts.
Mr. Clarke's transformer was connected by ordinary insulated wires with the moving air immediately above the foremast and the sea water beneath the keel of the Grande Duchesse. Down the vertical wire strung from the masthead the electric waves coming from the Ponce were carried into the receiving room of the Grande Duchesse and printed the dots and dashes upon an ordinary Morse instrument. The English international system was used. When the current from a powerful battery was turned for sending messages the perpendicular wire was readily charged and discharged and the message passed to its destination.
There were many passengers on the Grande Duchesse who were interested in the experiments carried on at the telegraph station aboard the ship. They crowded into the narrow cabin occupied by the mysterious instruments and puzzled over the connecting rows of batteries and yards of message-bearing tape. The young women and men on board carried away all the specimens they could obtain as souvenirs. More than five hundred persons saw the instruments during the six hours they were working and listened to the predictions of scientific men relating to their future.
Among the visitors were: General Felix Agnus, Anthony W. Brady, William S. Clarke, Maurice Gran, E. Berry Wall, Charles R. Flint, James S. Dumont and Al Hayman.