118 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 
The general principles on which practical radiotelegraphy is based 
are now so well known that I need only refer to them in the buelene 
possible manner. 
Wireless telegraphy, which was made possible by the fields of 
research thrown open by the work of Faraday, Maxwell, and Hertz, is 
operated by electric waves, which are created by Bloons currents 
of very high frequency, induced in suitably placed elevated wires or 
capacity areas. These waves are received or picked up at a distant 
station oh other elevated conductors tuned to the period of the waves, 
and the latter are revealed to our senses by means of appropriate 
detectors. 
My original system as used in 1896 consisted of the arrangement 
shown diagrammatically in figure 1, where an elevated or vertical wire 
was employed. 
: This wire some- 
; times terminated 
in a capacity or 
was connected to 
earth through a 
spark gap. 
By using an in- 
duction coil or 
other source of 
sufficiently high 
tension electricity 
sparks were made 
to jump across the 
gap; thisgave rise 
to oscillations of 
high frequency 1 in 
the elevated conductor and earth, with the result that energy in the 
form of electric waves was radiated through space. 
At the receiving station (fig. 2) these waves induced oscillatory 
currents in a conductor containing a detector, in the form of a coherer, 
which was usually placed between the elevated conductor and earth. 
Although this arrangement was extraordinarily efficient in regard 
to the radiation of electrical energy, it had numerous drawbacks. 
The electrical capacity of the system was very small, with the 
result that the small amount of energy in the aerial was thrown into 
space in an exceedingly short period of time. In other words, the 
energy, instead of giving rise to a train of waves, was all dissipated 
after only a few oscillations, and, consequently, anything approaching 
good tuning between the transmitter and receiver was found to be 
unobtainable in practice. 
Fig. 1. Fig. 2. 
