Electric Arc Wave Longer.

New York Times 100 years ago today, April 17, 1913:
Salem Radio Tests Show It Far Exceeds Spark Apparatus Energy. Special to The New York Times.
    WASHINGTON, April 16.— Reports to the Navy Department regarding the experiments conducted on the recent voyage of the scout cruiser Salem to Gibraltar to test the Arlington naval radio plant reveal a fact of great value in that there appear to be wave phenomena in the ether surrounding the earth. It has been demonstrated that between the two types of radiation, the spark apparatus and the electric arc, or "undamped" oscillations, the latter is less modified by absorption as each progresses over the face of the earth.
    The spark waves have proved to be less energetic up to a distance of several hundred miles. In the experiments with the Salem both types of transmission were used, and up to 900 miles distance it was found that there was little if any appreciable difference in their respective energy.
    It was possible in the daytime to communicate with the Salem from Arlington with both types, equally up to 2,100 miles, and at night communication with the Salem was easily maintained at Gibraltar. But beyond the distance of 2,000 miles it was discovered that the waves produced from the electric arc showed an increasing efficiency and possessed an energy four times as great as those from the spark apparatus.
    The discovery makes it necessary to conduct further experiments along the same line, and the plan is under consideration of sending the Salem out again, this time to the Mediterranean, to continue the trials at a gradually increasing distance.