Happy to see this post on HN. As a college prof, I've spend many years studying the history of 1700s navigation and taking student groups to Greenwich to see and study H1 (H2, H3 and H4). I love these clocks and all of the stories behind them. The serious enthusiast will find a lot of technical details on the Harrison's clocks in this book https://www.amazon.com/Marine-Chronometers-Greenwich-Catalog... and this one https://www.amazon.com/Marine-Chronometer-Its-History-Develo.... I've also collected all of my pedagogy on 1700s navigation into a this book: https://www.amazon.com/Longitude-Time-Navigation-Tom-Bensky-... where I dive somewhat into the innards of H1. To answer another post: H1 has been fully disassembled and reassembled with XRF done throughout.
Interesting features of John Harrison's sea clocks
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Re: Interesting features of John Harrison's sea clocks
#22If you're interested in the subject, the book "Longitude" by Dava Sobel (mentioned in Resources) is a very good read with lots of historical perspective on how these clocks were built.
Seconded! It is a wonderful book. Also an easy read and not very long.
I can't agree more, I've not seen a better book on the subject and Sobel's writing makes it an enjoyable read (I still have my copy of it).
Re: Interesting features of John Harrison's sea clocks
#23If you're interested in the subject, the book "Longitude" by Dava Sobel (mentioned in Resources) is a very good read with lots of historical perspective on how these clocks were built.
I was lucky enough to come across this book in elementary or middle school and found it absolutely mind blowing. In retrospect it exposed me to what are still among the most important ideas sloshing around my brain:
1. The realization of how much of the world has to be “invented.” Latitude and longitude didn’t strike me as an invention, but they are, and more interestingly longitude specifically is a conceptual invention that more or less had to sit downstream of a rather immense physical invention (Harrison’s clocks).
2. “The world has a surprising amount of detail”: as evidenced by looking at H1, H2, etc… there’s a lot you have to account for to achieve the apparently simple task of measuring time aboard a ship.
3. The social components to invention/discovery/progress: The competitions, funding/lack thereof, the need for “evangelism” around the different approaches, the need to find patrons (VC’s basically) to create a breakthrough, etc.
This book would make a great gift to an intellectually-inclined young person in your family!
Re: Interesting features of John Harrison's sea clocks
#24Happy to see this post on HN. As a college prof, I've spend many years studying the history of 1700s navigation and taking student groups to Greenwich to see and study H1 (H2, H3 and H4). I love these clocks and all of the stories behind them. The serious enthusiast will find a lot of technical details on the Harrison's clocks in this book https://www.amazon.com/Marine-Chronometers-Greenwich-Catalog... and this one h…
"...fully disassembled and reassembled with XRF done throughout.
Well, hopefully, that answers my point about the clocks' materials and an XRF analysis. Did that reveal anything of significance?
From points/questions raised by James Stanley and my ignorance of this recent work it seems these facts ought to be more widely known. (Ouch, the price of Marine Chronometers at Greenwich unfortunately has to mean that information is confined to Diehards.)
Re: Interesting features of John Harrison's sea clocks
#25Happy to see this post on HN. As a college prof, I've spend many years studying the history of 1700s navigation and taking student groups to Greenwich to see and study H1 (H2, H3 and H4). I love these clocks and all of the stories behind them. The serious enthusiast will find a lot of technical details on the Harrison's clocks in this book https://www.amazon.com/Marine-Chronometers-Greenwich-Catalog... and this one h…
Is there a way to buy your "Longitude, Time and Navigation" book as a physical book?
Re: Interesting features of John Harrison's sea clocks
#26Fascinated by "lignum vitae" mentioned several times. A little googling and I'm even more intrigued by this special wood. Example, one of the first results to come up: https://www.core77.com/posts/25224/lignum-vitae-wood-so-bad-...
Sadly it is an endangered species so it is illegal to trade now, I understand the best way to get it is to buy antique crown-green bowls and cut them up.
Didn't know Crown Green Bowls was a game — and I assume it's the balls that are made from Lignum Vitae.
Re: Interesting features of John Harrison's sea clocks
#27Earlier quoted context omitted.
Sadly it is an endangered species so it is illegal to trade now, I understand the best way to get it is to buy antique crown-green bowls and cut them up.
Didn't know Crown Green Bowls was a game — and I assume it's the balls that are made from Lignum Vitae. https://en.wikipedia.org/wiki/Crown_green_bowls
Yes, the balls are (historically) lignum vitae. I don't know why they're called bowls instead of balls.
Re: Interesting features of John Harrison's sea clocks
#28If he made the most accurate clock in the world, how would he know?
The prize here was for most accurate at sea, so compare with more accurate land clocks. But in general?
If salt should lose its savour, with what shall it be salted?
... tried feeling bits of himself to see where he might be hurt. Wherever he touched himself, he encountered a pain. After a short while he worked out that this was because it was his hand that was hurting.a
Re: Interesting features of John Harrison's sea clocks
#29If he made the most accurate clock in the world, how would he know? The prize here was for most accurate at sea , so compare with more accurate land clocks. But in general? If salt should lose its savour, with what shall it be salted? ... tried feeling bits of himself to see where he might be hurt. Wherever he touched himself, he encountered a pain. After a short while he worked out that this was because it was his h…
I think he watched for a particular star to disappear behind his neighbour's chimney, from a fixed vantage, on the understanding that this should always take exactly 1 day, and by measuring how many seconds have elapsed on your clock you know how well your clock has kept time over the previous day.
Re: Interesting features of John Harrison's sea clocks
#30After reading Dava Sobel's book 20 years ago I made sure to go to Greenwich to see the clocks when I was in London in 2005. They are both amazing engineering and works of art.