I'd also recommend this book. It's sitting on my shelf - I had to hunt down a copy as I remembered reading it when I was a kid. Couldn't find a digital/kindle copy but I feel like reading the paper version works with the topic of the book, too.

Super well written and very cool to read about not just the technology side of telegraphy but the culture as well, and how it still roughly mirrors culture found when the book was written all the way up till now.