If you're interested in telegraph's and early communications technology, I HIGHLY recommend getting a copy of "The Story of Telecommunication" by George P. Oslin [1]. It's very thoroughly researched and clearly a labor of love. tchingazing video on YouTube.

Also, I can't help but share this awesome video I recently found - "How the Teleprinter Works" [2]. It's fascinating and very well done.

[1]: https://www.amazon.com/STORY-TELECOMMUNICATIONS-George-P-Osl...

[2]: https://youtu.be/HcMHam54EOI