This area of the museum contains toll devices, telegraph and teletype machines.
This department of the telephone company was responsible for services such as
cross country calling, dedicated (private) lines, secure communications both
voice and data, telegraph and teletype. There are many types of devices
represented of each type.
The telegraph was invented by Samuel Morse in the 1840's. It is a device to
communicate between two remote locations. Operators on either end of the line
would send and receive messages using a series of electrical pulses (short
pulse is a dot) and dashes (which were three times longer.) Each pattern of
dots and dashes represented a letter, for example an A is
.
- , a B is -
...
and so forth. The sending operator would send a message letter by letter and
the receiving operator would write it down.
Thomas Edison saved the life of young girl who was almost run over by a train. The girl's father to repay Edison, taught him Morse code and Thomas Edison worked as a Morse code operator for a number of years. Morse code preceded the invention of the telephone by about 35 years.
The devices shown in the picture from left front to right are a telegraph key and a local sounder, a Vibroplex key (bug), a sounder and in back another sounder.
Teletype machines were useful because they produced a written paper copy of the
transmitted message. The museum has many different types of teletype machines
from the year 1918 and forward. Over 30 types are displayed at the museum
including a German teletype built by the Lorentz Company. The Lorentz Company
built the Enigma which was a German device that turned text into encrypted
messages during WWII. Teletype machines were used by the FBI, commercial
airlines, stockbrokerage firms, and the wire services like Associated Press
(AP) and United Press International (UPI) to distribute the news to newspapers
and radio broadcasts.
The A5 channel bank was used to stack voice grade circuits in a LMX carrier
system. The upper unit is a 4 kilohertz carrier supply and when combined with a
harmonic generator provided 600 carrier frequencies for microwave transmission
carrying voice grade and data circuits. The equipment on the bottom is a first
generation solid state (transistorized) A-5 channel bank. It provided 12 single
sideband voice grade circuits that were stepped up in frequency for
transmission.