164 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
Admiral Sir Henry Jackson, to whom the country is so much indebted 
in this matter, informs me that every ship above the size of a torpedo 
boat is or will soon be fitted. Large battle ships carry fairly high- 
power transmitters for long-distance work. The Admiralty are satis- 
fied that this method of signaling is of the greatest utility, and there 
is no need to remind you of the evidence of this furnished in the re- 
cent Russo-Japanese war. No modern liner or large passenger vessel 
is now complete without a wireless telegraph equipment, and an 
elaborately organized system of communication has been created by 
the Marconi Company in connection with this marine telegraphy. 
Concurrently with this practical development of the art, much 
scientific investigation has been conducted, having for its object the 
elucidation and measurement of the various physical operations in- 
volved, as well as further improvement. There comes a time in the 
history of every applied science when the ability to measure precisely 
the effects concerned is a condition of further progress. It is this 
alone which enables us to test our 
theories, or hold in leash hasty 
opinions as to the possibilities of 
the invention. 
In considering, then, during the 
present hour some of the recent 
contributions to this new telegra- 
phy, we may pay a moment’s at- 
tention to the nature of the things 
Fic. 1.—Lines of electric foree round an or effects in 1t which can be meas- 
a Mee aes ured. An essential element in all 
electric wave telegraphy is the elevated insulated wire or wires 
called the ahtenna, in which high frequency electric currents are 
set up, and from which the electric waves radiate. Consider a long 
vertical wire, insulated completely from the earth and charged 
with electricity. (See fig. 1.) There must be somewhere on the 
surface of the earth near by a charge of opposite sign. If the wire 
is negatively charged, then, on its surface, there is, according to 
modern views, an excess of negative ions or electrons, and on the 
ground surface round the wire there is a deficiency, that is, there 
is a positive charge. Furthermore, in the interspace around the rod 
there is a state of strain of some kind distributed along certain curved 
lines, commonly called lines of electric force. From one point of view 
these lines may be regarded simply as a convenient mode of deline- 
ating the direction of the strain, having not more material reality 
than lines of latitude and longitude. There are, however, some rea- 
sons for considering that they do possess an actual physical existence, 
and that they are a necessary part of the mechanism of atoms and 
