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Comment by logicallee | Hacker News Reader

> To determine the speed, you count how many knots pass through your hand in a certain time.

But how did they count "a certain time"? (Before stopwatches).

The origins of precise clocks is because ships needed to calculate how far they had travelled in terms of longitude (eastwast/westward. How far you've travel north/south is easy to calculate by how high the sun goes).

The British crown established an award for whoever could come up with a precise clock of this reason, it's a fascinating story, I recommend the book "Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time" by Dava Sobel.

Also if you're interested in inventors from the late 17th Century, I highly recommend: "The Man Who Knew Too Much: The inventive life of Robert Hooke"

https://en.wikipedia.org/wiki/Marine_sandglass

Sandglasses were around for a long time.

Well, we assume it was a long time but maybe sandglasses were really inaccurate.

I'm not sure if it would matter if they were really inaccurate if the ship used the same sandglass and rope. I've read about the shipping log -> world map work [1] where it details that the speeds/distances for a given group of boats had different errors which the gentlemen developed a technique to resolve.

[1] https://priceonomics.com/a-map-of-the-world-made-from-shippi...

Mechanical pocket watches or ship's clocks. They were expensive but accurate enough.

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