Sextant by David Barrie is the story of the navigational instrument of that name.
It tells the history of its development and some of the great voyages that were possible using its ability to accurately measure angles from a pitching and rolling deck.
The book is framed by the story of the author's first transatlantic sail as a teenager with a family friend, Colin, and his cousin (Colin's that is, not David's) Alexa, also a teenager.
It's well written and I found it interesting, even though it covered the same ground as other sailing history books I've read. It linked explorers and sailors such as Cook, Vancouver, Flinders, Fitzroy, Slocum, Bligh and Shackleton together via their navigational tools.
It even ends up with a pitch for natural navigation and a reference to Tristan's book.
The only unanswered question was what it had been like as a teenage boy to spend weeks in close proximity to a teenage girl, namely Alexa, in that first transatlantic crossing. Maybe its time to add Dove to my reading list.
Overall a recommended read about one of offshore sailing's key navigational tools.