For proper navigation, we need to know the accurate time. This is a centuries old challenge. The solution took place in Greenwich, UK just outside of London. So, what could be a better way to check our clocks on the boat than to pop over to London to use the official clock for Universal Coordinated Time that is maintained at Greenwich? While there, I took the time to stand in both hemispheres across the prime meridian. The eastern hemisphere was nice, but we’ll keep Hurrah in the western hemisphere for now.
The story of the search for longitude is a ripping tale. Back in the 18th century, there was a long line of ships wrecking on various coasts due to inaccurate position fixes. To make things really simple, an easy way to get the longitude of your position, is to observe the sun at local noon time (not a time zone time, but literally when the sun hits its zenith in the sky at a particular place on the earth – where the observer is).
To figure out longitude, however, you need to know what time it is somewhere else on the globe. Back then London was a common base reference, though Paris and other locations were used as well. Clocks back then were terrible and were even worse on a damp and constantly moving ship. Errors were on the order of minutes a day. This translates into huge position errors.
Parliament set up a prize of 20,000 sterling (approx 7 million sterling/$13 million) for anyone who solved the problem and empowered the Royal Observatory at Greenwich to award the big prize and smaller prizes.
There were two schools of thought. The astronomers who occupied the highest levels of learning and prestige at the time looked for celestial techniques to figure out time. Again in simple terms, they could use the distance of the moon to some other celestial body and use this to figure out what time it was (because they knew when the moon would be at that distance) or some other celestial event.
Then, the clockmakers, led by a relatively uneducated, young (at the start) John Harrison worked on building better clocks. Harrison was unknown, but declared he could solve it. He was able to secure a grant and built what is now called H1 out of brass and wood (lingum vitae):
H1 was really good – much better than any other at the time. But, not quite good enough.
So, he built H2 from 1737 to 1740.
H2 was really good. It had improved temperature compensation and a better frame, but it was still impacted by the movement of the ship. He had better ideas. So, he spent 19 years building H3 which had over 700 intricate parts.
H3 had many improvements, but it was unstable and wouldn’t have been a good clock to take to sea. So, he dramatically changed his approach and built H4. Looks a bit different, eh?
It wouldn’t fit in a pocket, but close. Then the story is full of disputes as you can imagine might be involved in handing out so much money. Harrison eventually received full amount of the money 3 years before he passed away.
Seeing the clocks was amazing. And, to top it off, all the clocks were running. Plus, the astronomy exhibits were really well done. Greenwich was a phenomenal sight to see especially given these clocks. As a bonus, now our clocks on Hurrah are good to go.
If you go to London, go to Greenwich. It’s worth the trip.