The Birmingham age-herald., 1902-10-09
COMMERCIAL UTILITY OF
 WIRELESS TELEGRAPHY

From the Report to the Census Bureau
 Oust issued) by T, commerford Martin.
 special agent.
 One of the latest and most important developments in telegraphy Is that to which the epithet of .wireiesu' has been attached, although thls is neither aoeu- rate nor descriptive. as there Is more or less wire in the circuit fin spite of the fact that none stretches between the trans- hitting and receiving apparatus in the old and familiar manner Wireless tell egraphic apparatus still remains to some degree mysterious to the public. but has been in commercial use for several years, and was a regular manufacture during the census year. although the work in America at that time was still largely ex- perimental. The most prominent worker in this field Is c. Marconi. an Anglo-Ital- ian, who has already transmitted signals between the English and North American shores of the Atlantic through the air. a distance of nearly 5000 miles, and whose commercial work over shorter distance is being rapidly developed as the result of his experiments, beginning as far back as 1s95-0G,
 Tn passing Is should be noted that wire less telegraph systems of 6 different na- true had already been developed In this country several years ago by MT. Edison and others, depending upon the principle of induction, and employed more specih- cally as a means of telegraphlng to and from moving trains. In this work induc- tive signals are jumped across the air space between the ordinary telegraph wire on the track and the metallic roof of the passing car, which contains the re- ceiving apparatus, and the Signals are recorded by means of buzzing dots and dashes heard in a telephone in the receiv- ing circuit. In the same manner the op- orator on the car desiring to send a mes sage dePresses his own key. which causes an inductive coil to operate by local bat tery, through a vibrator to charge and discharge the car roof at a high potential and rapid rate. These effects, core spending to dots and dashes, are taken up by the ordinary parallel wires along
 
 will hear the dots and dashes in his tel ephone, and thus receive a message. It is recorded that messages have thus been sent over spaces of between 300 and 400 feet from the condenser roof of the car and the telegraph wires, with the train running at forty miles an hour Other developments by MT. Edison in this field include the use of condensing metallic surfaces and static effects to signal at considerable distances, using balloons, the sails of ships, etc.
 It remains, however, for Mir Marconi and other workers in this field to accom- plish the feat of transmitting telegraphic signals without wires through distances of hundreds of miles, employing what are known as "Hertzian waves,'' or infiu- ences imposed electrically upon the ether by electromagnetic apparatus, these waves being detected only by special ap- paratus of the most delicate character. In MT. Marconi's work the transmitting apparatus consists essentially of a spe- cial induction coil, which has one side of the secondary spark gap in the sec ondary circuit, connected with the ground; and the other connect ed with a vertical wire carried up some distance into the air by pole or by a kite or balloon. The two gap spheres are also connected with the ends of the secondary winding of the induction coil or trans former The spheres are not always es- sential. When the operator in transmit ting presses his key, the current from the battery energlzes the induction or spark coil, which in turn charges the spheres and the vertical wire in such a manner that electrical disturbance is thrown off by the vertical wire in the form of dis