Compasses

[Bob Aberton]

I don't know much about orienteering compasses, but in ship's compasses (ie binnacled compasses), the compasses usually have to be equipped with an iron Flinder's bar and maybe quadrantial spheres, which are also made of iron; they're supposed to eliminate compass deviation caused by a ship's hull. Even in wooden ships, large masses of metal such as the anchor and sometimes the wheel (if it's one of those fancy chrome-steel wheels) can throw off the compass.

I would imagine that a handheld compass would be thrown off somewhat by armor, but probably just holding it at arm's length would eliminate the problem...

 

[isoChron]

A fighter in full plate with a great axe qualifies for deflecting the compass needle in my book.

By the way: the pole is moving so it seldom shows true north. Now imagine the Faerunian pole moving even faster or deviate much farther from true north than the magnetic pole on earth (today).
Underground a compass often deflects from ore veins or simply from lava flows with a high Iron content. On icelandic lavaflows there are several problems using a compass. And so on and so on.... Just use the old moss-on-a-tree-method, the direction of sun and stars or the intuitive sense of some people instead of a technical compass. Few people had a compass in the middle ages (except ship-captains).

And isn't it more fun to send the group to some place where they don't want to be ?

BYE

 

[Agback]

Re: Tolkien's Essay on Fairy Stories, Compasses, and Experimental Evidence:

Conclusion: It is the inverse square law, with a vengeance!

If I recall Physics 5.006 correctly, magnetic fields decline as an inverse cube (because they are the residuals of electrical fields).

Regards,


Agback

 

[Agback]

The compass was probably invented about the tenth century, somewhere in the Orient (China is suspected). By the thirteenth, it was in common use throughout Europe. It certainly fits into Medieval technology...

So why no compasses in any version of D&D?

Because [default] D&D doesn't actually have a mediaeval setting. It has a vanilla fantasy setting that includes things that wouldn't work in practice but that appeal to the tastes of props men and set decorators on B-grade fantasy grunt-flicks, and excludes everything that half-educated directors expect un-educated audiences to think of, in a vague way, as 'technology'.

You might as well ask why D&D has armour spikes, locked gauntlets, and ten-pound swords. And consider yourself lucky that your character can climb onto a horse while wearing plate armour.

Regards,


Agback

 

[Conaill]

Not 100% core rules, but WotC's very own Arms & Equipment Guide does have magnets (10 gp, 1lb, used to pick things up), as well as a navigator's kit including a sextant, astrolabe, compass and measuring tools (250 gp, 8 lb, +2 Intuit Direction, Wilderness Lore (for direction) at sea, and Profession (Cartographer).

Mongoose's Ultimate Equipment Guide also has a gnomish "Southfinder" (100 gp, +2 Intuit Direction if you have at least 4 ranks). I've seen similar tools in a variety of other sources as well.

 

[Steverooo]

You might as well ask why D&D has armour spikes, locked gauntlets, and ten-pound swords. And consider yourself lucky that your character can climb onto a horse while wearing plate armour.

Thanks for the info on inverse cubed... Didn't know that, either!

As for the other stuff, I DO ask those questions (especially "How do you spike chainmail?")! Ten pound swords (and five pound handaxes) are crazy. Spiked cloth is nearly as bad... but that has nothing to do with compasses, so please don't get me started!