How are messages transmitted through telegraphy?

Telegraphy is a method of transmitting messages over a distance using electrical signals. It was developed in the early 19th century and was used extensively for long-distance communication before the advent of the telephone. Here's a general overview of how messages are transmitted through telegraphy:

1. Encoding the Message:

- The message to be transmitted is first encoded into a series of dots and dashes using a code such as Morse code. Each letter of the alphabet, number, and punctuation mark is represented by a unique sequence of dots and dashes.

2. Transmitter:

- A telegraph transmitter, often called a telegraph key, is used to send the encoded message as electrical signals.

- When the telegraph key is pressed, it completes an electrical circuit, sending an electrical current along the telegraph wire.

- When the key is released, the circuit is broken, interrupting the current.

- The duration and pattern of these electrical pulses correspond to the dots and dashes of the Morse code.

3. Telegraph Wire:

- The electrical signals travel through a telegraph wire, which can be a single wire or a pair of wires.

- The telegraph wires were typically made of copper or iron and could be strung over poles, buried underground, or even laid underwater for long-distance communication.

4. Receiver:

- At the receiving end, a telegraph receiver, often called a sounder or a relay, detects the incoming electrical signals.

- The sounder consists of an electromagnet that converts the electrical pulses into audible sounds.

- When an electrical pulse is received, the electromagnet attracts a metal armature, producing a clicking sound.

- The pattern of these clicks corresponds to the dots and dashes of the Morse code.

5. Decoding the Message:

- The receiving operator listens to the sequence of clicks and interprets them back into the original message using Morse code.

- The decoded message is then written down or printed on a paper tape for the recipient.

6. Repeaters:

- For longer distances, telegraph signals could become weak and distorted due to resistance and capacitance in the wires.

- To overcome this, telegraph repeaters were used at intervals along the line to amplify and regenerate the signals, ensuring reliable transmission over longer distances.

Over time, telegraphy evolved with advancements in technology, such as the use of duplex systems for simultaneous two-way communication and the development of automatic telegraph machines that could transmit and receive messages at higher speeds. However, with the introduction of more advanced communication methods like the telephone and radio, telegraphy gradually declined in the 20th century.