sages not at all. It was also
found that messages passed without hindrance, even though the train
was passing through a tunnel.

Another interesting application of wireless telegraphy is to the
needs of the fire-fighters. Fire stations in New York City have been
equipped with wireless telegraph sets, and they have proved so useful
in spreading alarms and transmitting news of fires that they seem
destined to come into universal use.

The outbreak of the world war gave a tremendous impetus to the
development of wireless telegraphy. The German cable to the United
States was cut in the early days of the conflict. The sending power
of wireless stations had been sufficiently increased, however, so that
the great German stations could communicate with those in the United
States. Communication was readily maintained between the Allies by
means of wireless, the great stations at Poldhu and at the Eiffel
Tower in Paris being in constant communication with each other and
with the stations in Italy and in Russia.

Portable field sets had been used with some slight success even in the
Boer War, and had definitely proved their worth in the Balkans. The
outbreak of the greater war found all of the nations equipped with
portable apparatus for the use of their armies. These proved of
great use. The field sets of the United States Army also proved their
utility in the campaign into Mexico in pursuit of Villa. By their
means it was possible for General Pershing's forces to keep in
constant touch with the headquarters in the United States.

The wireless proved as valuable to the navies as had been anticipated.
The Germans in particular made great improvements in light wireless
sets designed for use on aircraft. The problem of placing an aerial on
an aeroplane is difficult, but no little headway has been made in this
direction.

It is the American boy who has done the most interesting work with the
wireless in the United States. While the commercial development
has been comparatively slow, the boys have set up stations by the
thousands. Most of these stations were constructed by the boys
themselves, who have learned and are learning how best to apply this
modern wonder to the service of man. So many amateurs set up stations
that the Government found it necessary to regulate them by law.
The law now requires that amateur experimenters use only short
wave-lengths in their sending, which will not interfere with messages
from Government