But even more wonderful things were to come. Early in the morning of the next day other messages were sent from the Arlington tower, and these messages were heard by Lloyd Espenschied, one of Carty's engineers, who was stationed at the wireless station at Pearl Harbor, near Honolulu, Hawaii. The distance covered was nearly five thousand miles, and half of it was across land, which is the more remarkable as the wireless does not operate so readily over land as over water. The distance covered in this test was greater than the distance from Washington to London, Paris, Berlin, Vienna, or Petrograd. The successful completion of this test meant that the capitals of the great nations of the world might communicate, might talk with one another, by wireless telephone. Only a receiving set had been installed at Hawaii, so that it was not possible for Espenschied to reply to the message from Arlington, and it was not until his message came by cable that those at Arlington knew that the words they had spoken had traveled five thousand miles. Other receiving sets had been located at San Diego and at Darien on the Isthmus of Panama, and at these points also the words were distinctly heard.
By the latter part of October all was in readiness for a transatlantic test, and on the 20th of October American engineers, with American apparatus installed at the great French station at the Eiffel Tower, Paris, heard the words spoken at Arlington, Virginia. Carty and his engineers had bridged the Atlantic for the spoken word. Because of war-time conditions it was not possible to secure the use of the French station for an extended test, but the fact was established that once the apparatus is in place telephonic communication between Europe and America may he carried on regularly.
The apparatus used as developed by the engineers of the Bell system was in a measure an outgrowth of their work with the long-distance telephone. Wireless telephony, despite the wonders it has already accomplished, is still in its infancy. With more perfect apparatus and the knowledge that comes with experience we may expect that speech will girdle the earth.
It is natural that one should wonder whether the wireless telephone is destined to displace our present apparatus. This does not seem at all probable. In the first place, wireless telephony is now, and probably always will be, very expensive. Where the wire will do it is the more economical. There are many limitations to the use of the other for talking purposes, and it cannot be drawn upon too strongly by the man of science. It will accomplish miracles, but must not be overtaxed. Millions of messages going in all directions, crossing and recrossing one another, as is done every day by wire, are probably an impossibility by wireless telephony. Weird and little-understood conditions of the ether, static electricity, radio disturbances, make wireless work uncertain, and such a thing as twenty-four-hour service, seven days in the week, can probably never be guaranteed. In radio communication all must use a common medium, and as its use increases, so also do the difficulties. The privacy of the wire is also lacking with the wireless telephone.