In the most recent Marconi transmitter the current produced is no longer in the form of intermittent sparks, but is a true alternating current, which in general continues uniformly as long as the key is pressed down.
There is no longer any question that wireless telegraphy is here to stay. It has passed the juvenile stage and is fast approaching a lusty adolescence which promises to be a source of great strength to the commerce of the world. Already it has accomplished much for its age. It has saved so many lives at sea that its installation is no longer regarded as a scientific luxury but a practical necessity on every passenger vessel. Practically every steamer in American waters is equipped with a wireless station. Even freight boats and tugs are up-to-date in this respect. Every ship in the American navy, including colliers and revenue cutters, carries wireless operators. So important indeed is it considered in the Navy department that a line of shore stations have been constructed from Maine on the Atlantic to Alaska on the Pacific.
In a remarkably short interval wireless has come to exercise an important function in the marine service. Through the shore stations of the commercial companies, press despatches, storm warnings, weather reports and other items of interest are regularly transmitted to ships at sea. Captains keep in touch with one another and with the home office; wrecks, derelicts and storms are reported. Every operator sends out regular reports daily, so that the home office can tell the exact position of the vessel. If she is too far from land on the one side to be reached by wireless she is near enough on the other to come within the sphere of its operations.
Weather has no effect on wireless, therefore the question of meteorology does not come into consideration. Fogs, rains, torrents, tempests, snowstorms, winds, thunder, lightning or any aerial disturbance whatsoever cannot militate against the sending or receiving of wireless messages as the ether permeates them all.
Submarine and land telegraphy used to look on wireless, the youngest sister, as the Cinderella of their name, but she has surpassed both and captured the honors of the family. It was in 1898 that Marconi made his first remarkable success in sending messages from England to France. The English station was at South Foreland and the French near Boulogne. The distance was thirty-two miles across the British channel. This telegraphic communication without wires was considered a wonderful feat at the time and excited much interest.
During the following year Marconi had so much improved his first apparatus that he was able to send out waves detected by receivers up to the one hundred mile limit.
In 1900 communication was established between the Isle of Wight and the Lizard in Cornwall, a distance of two hundred miles.
Up to this time the only appliances employed were induction coils giving a ten or twenty inch spark. Marconi and others perceived the necessity of employing greater force to penetrate the ether in order to generate stronger electrical waves. Oil and steam engines and other appliances were called into use to create high frequency currents and those necessitated the erection of large power stations. Several were erected at advantageous points and the wireless system was fairly established as a new agent of communication.
In December, 1901, at St. John's, Newfoundland, Marconi by means of kites and balloons set up a temporary aerial wire in the hope of being able to receive a signal from the English station in Cornwall. He had made an arrangement with Poldhu station that on a certain date and at a fixed hour they should attempt the signal. The letter S, which in the Morse code consists of three successive dots, was chosen. Marconi feverishly awaited results. True enough on the day and at the time agreed upon the three dots were clicked off, the first signal from Europe to the American continent. Marconi with much difficulty set up other aerial wires and indubitably established the fact that it was possible to send electric waves across the Atlantic. He found, however, that waves in order to traverse three thousand miles and retain sufficient energy on their arrival to affect a telephonic wave-detecting device must be generated by no inordinate power.
These experiments proved that if stations were erected of sufficient power transatlantic wireless could be successfully carried on. They gave an impetus to the erection of such stations.