Radio____ 3907

intf oil and mineral deposit*, in detecting
flaw.-, in metals and in developing high lever
In liuman.s. The development of bruadcast-
nL* has probably been more extensive in the

Radio

United Si at is than in any

country.

The fact that over ooo .stations are in oper-
ation, ahout half of them simultaneously,
has made tlu- piohU-m of frequency or wave
length aj^itfimienl a difficult one. Another
iMjL: development has heen the estab-
lishment of .short-wave stations for the trans-
mission of broadcasting programs to a dis-
tant fountry, primarily for the purpose of
re-t rant-mitt inn the program over the regu-
lar broadcast stations of that country. Valu-

othcr data that would advise of any danger-
ous condition that might interfere with the
safety of flying or landing.

The use of radio broadcast receivers in
automobiles is quite commonplace, and also
some taxicabs in the large cities are thus
equipped. Radio police service is proving
very valuable in the running -down of crime,
special radio equipped cars receiving informa-
tion from the transmitter at headquarters.
Since 1935, two-way radio communication
for police cars has come into general use
and has increased the efficiency of police
work. Passengers on air liners may now send
radio messages while en route. The joint use

Broadcasting: Auditorium Studio, Radio City.

able service was first rendered by radio com-
munication \vilh ships in distress at sea.
There are many instances on record where
radio has been responsible for the rescue of
human life. According to thtk provisions
adopted by the International Convention for
the Safety of Life at Sea, all passenger ves-
sels having a tonnage of 5,000 or over must
now carry radio direction finding equipment.
The successful application of radio to aircraft
communication involves the solution of many
additional problems not encountered in other
service, One of the, most valuable phases
of this service takes in the radio beacon
enabling the airplane to approximate its po-
sition and particularly to be able to easily
ascertain and closely follow the proper
course* Also of tremendous importance is
the service of supplying advance knowledge
of weather information. This include* any

of wire telegraph and telephone systems in
conjunction with radio or wireless systems
is rapidly becoming more widespread. At
present there arc about 30,000,000 telephones
throughout the world which afford means
of communication by the combined use of
wire and radio telephony. Telephone service
across the Atlantic Ocean was put on a full
time or 24 hour basis in September, 1929.
The service is well established for telephone
communication between any land telephone
subscriber and voyagers at sea on several
large ships. In 1941 there were 52,000,000
receiving sets in use in the U. S. Also 7,500,-
ooo cars were equipped with radio in 194*-
Perfection of short-wave radio and its com-
mercial production at a low retail price has
brought it into general use. The Federal
Communications Commission was established
in 1934 to regulate radio, succeeding the