132 



KECENT ADVANCES IN WIRELESS TELEGRAPHY. 



waves of light. F'ollowing up Maxwell, Hertz in 1887 furnished his 

 great practical proof of the existence of these true electro-magnetic 

 waves. 



Building on the foundations prepared by these great men, the 

 author carried out in 1895 and 189G his first tests, with apparatus 

 wdiich embodied the principle on which long-distance wireless teleg- 

 raphy is successfully worked at the present day. 



This early arrangement is shown in figures 1, 2, and 3, 



In figures 1 and 2 are shown diagrammatically the complete trans- 

 mitting and receiving plants, and in figure 3 are shown the circuits 

 of the receiving instruments. 



The main feature of the sj^stem is the utilization of the earth 

 effect by connecting both the transmitting and receiving instruments 

 between earth and a raised capacity. 



-....T 



The later improvements introduced in the author's system of wire- 

 less telegraph}' have been directed toward the following ends : 



1. To obtain independence of communication or the prevention of 

 interference between several neighboring stations. 



2. To increase the distance of communication. 



3. To increase the efficiency of the apparatus, its accuracy, and 

 working speed. 



One of the chief objections which is raised against wireless teleg- 

 raphy is that it is possible to work only two or a very limited number 

 of stations in the immediate vicinity of each other without causing 

 mutual interference or producing a jumble by the confusion of the 

 different messages. This objection appears to be much more serious 

 to that section of the public which knows little or nothing of teleg- 

 raphy in general than to telegi'aph engineers, who know that with- 

 out organization and discipline the same interference would occur in 

 the great majority of ordinary land telegrams. For example, there 

 is an ".omnibus " line between Cork and Crookhaven. On this line 

 there are a dozen or more telegraph offices, all with their instruments 

 joined up to the same wire running from the terminal stations. Now, 



