Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Components (hierarchy name)
4. components (objects parts)
5. [components by specific context]
6. system components
7. telecommunication systems components

Narrower term/s

• engine-room telegraphs

Anotations

Scope note:

Any of numerous types of devices or systems that allow the transmission of information by coded signal over a distance. Many telegraphic systems have been used over the centuries, but the term most often refers to the electric telegraph, which was developed in the mid-19th century and was the principal means of transmitting printed information by wire or radio wave for over a century. It consisted of a transmitting or sending instrument and a distant receiving instrument connected by a conducting wire or other communications channel.