Here's a little something that you probably didn't know. Compasses were set into binnacle boxes that were built off of the deck. The compasses were so sensitive that any iron (nails, copper sheathing, bolts, the rudder, hinges for doors) could mess up the compass reading. The best way to get a good reading was to build it about waist high. In addition, navigators had sextants, which were devices used to measure the distance between the sun or moon and the horizon. Earlier navigators used a T-Stick which was a staff with a Y carved into the top. It was used the same way, to get a good look at the distance between two objects, such as the deck and the top of the mast.
People should read this and study it. It would make their sailing descriptions much better.
This is all absolutely fascinating and written in such an engaging manner. I got a bit confused in the compass section: did you mean "because true north also drifts over time" or is it magnetic north which does that?
I dug a bit further and found out that true north can also wander (there's even a true polar (TPW) and apparent polar (APW) wander) as the tectonic plates also move. So you're right either way!
This whole topic is like disappearing into a snake hole in a rabbit burrow within a badger sett. 😛
Fascinating! And I totally felt the same way regarding the depth of the subject. I actually had many more paragraphs written in my first draft about magnetism and geology that I ended up removing because it strayed too far off-topic.
Great article! You covered a LOT of material very efficiently! I would love to read that hypothetical geology world-building article you mentioned!!
I feel compelled to nitpick the assertion that "Nobody noticed magnetic declination prior to The Age of Exploration because they generally never sailed or traveled far enough for it to matter." "Brush Talks from Dream Book" written by Shen Kuo in 1088 has the following passage (Wang Hong & Zhao Zheng's translation, 437. Magnetlc Compass):
> Diviners can make a needle point to the south by rubbing it with a magnetic stone. However the needle often inclines to the southeast direction, not pointing to due south. [...] The needle rubbed by a magnetic points to the south, just as the cypress tree leans to the west. Nobody knows the reason why it is so.
Though whether or how this observation was actually used by contemporary Chinese navigators I don't know. It certainly wouldn't be necessary for riverine or coastal navigation, relevant given China's many rivers and surrounding narrow seas.
Great stuff! Thanks for collecting all this information. Now I kinda want to write a story about pilots fighting for supremacy.
I will shamelessly plug a post I wrote discussing some of the things I've learned about sailing and the ocean, one of them being the struggle of finding longitude.
Thanks Kailani! And I’ll definitely check out your post! Honestly one of the reasons I didn’t tackle longitude and the sextant is because I have this whole book on its history that I have yet to crack open, so I’m eager to see what you have.
Here's a little something that you probably didn't know. Compasses were set into binnacle boxes that were built off of the deck. The compasses were so sensitive that any iron (nails, copper sheathing, bolts, the rudder, hinges for doors) could mess up the compass reading. The best way to get a good reading was to build it about waist high. In addition, navigators had sextants, which were devices used to measure the distance between the sun or moon and the horizon. Earlier navigators used a T-Stick which was a staff with a Y carved into the top. It was used the same way, to get a good look at the distance between two objects, such as the deck and the top of the mast.
People should read this and study it. It would make their sailing descriptions much better.
This is all absolutely fascinating and written in such an engaging manner. I got a bit confused in the compass section: did you mean "because true north also drifts over time" or is it magnetic north which does that?
I’m glad this was helpful, Johnathan! And sorry for the confusion: it’s magnetic north that drifts. Apparently as of now it’s headed for Siberia.
I dug a bit further and found out that true north can also wander (there's even a true polar (TPW) and apparent polar (APW) wander) as the tectonic plates also move. So you're right either way!
This whole topic is like disappearing into a snake hole in a rabbit burrow within a badger sett. 😛
Fascinating! And I totally felt the same way regarding the depth of the subject. I actually had many more paragraphs written in my first draft about magnetism and geology that I ended up removing because it strayed too far off-topic.
Great article! You covered a LOT of material very efficiently! I would love to read that hypothetical geology world-building article you mentioned!!
I feel compelled to nitpick the assertion that "Nobody noticed magnetic declination prior to The Age of Exploration because they generally never sailed or traveled far enough for it to matter." "Brush Talks from Dream Book" written by Shen Kuo in 1088 has the following passage (Wang Hong & Zhao Zheng's translation, 437. Magnetlc Compass):
> Diviners can make a needle point to the south by rubbing it with a magnetic stone. However the needle often inclines to the southeast direction, not pointing to due south. [...] The needle rubbed by a magnetic points to the south, just as the cypress tree leans to the west. Nobody knows the reason why it is so.
Though whether or how this observation was actually used by contemporary Chinese navigators I don't know. It certainly wouldn't be necessary for riverine or coastal navigation, relevant given China's many rivers and surrounding narrow seas.
That's fascinating, and thank you for the correction! I'm going to add it to the article. As for the geology guide, that will come with time for sure!
Great stuff! Thanks for collecting all this information. Now I kinda want to write a story about pilots fighting for supremacy.
I will shamelessly plug a post I wrote discussing some of the things I've learned about sailing and the ocean, one of them being the struggle of finding longitude.
https://damselinthelibrary.substack.com/p/the-sea-and-all-its-devils
I'd be interested in any other worldbuilding guides you want to write.
Thanks Kailani! And I’ll definitely check out your post! Honestly one of the reasons I didn’t tackle longitude and the sextant is because I have this whole book on its history that I have yet to crack open, so I’m eager to see what you have.