I would like a mechanism, preferably pre-1700, that makes a specifically 'calibrated' compass point towards the mechanism anywhere on the planet instead of the poles. I'd also like if this mechanism doesn't interfere with other compasses or messes with other things that rely on magnetic fields.

Edit: The mechanism is in a fixed position.

Edit 2: Pre-1700 is not a requirement, but is appreciated.

  • $\begingroup$ Is the other mechanism's position fixed (like Ka'abah), or it can be moving? $\endgroup$
    – Alexander
    Commented Jun 24, 2020 at 23:18
  • $\begingroup$ It's in a fixed position. $\endgroup$ Commented Jun 24, 2020 at 23:20
  • 1
    $\begingroup$ Electronics would be unhelpful anyways, since radio navigation finding gets weird once you get sufficiently over the horizon. The other side of the world is almost certainly out. You can do this with some really good clocks and gyrocompasses, it looks like, although that's very definitely 1800's plus (almost 1900s). Note that such a device would point to "any" calibrated point, not your specific mechanism. $\endgroup$ Commented Jun 25, 2020 at 6:23
  • $\begingroup$ Gyrocompasses get weird over time if you travel long distances, since you travel along the curving surface of the planet. $\endgroup$ Commented Jun 25, 2020 at 7:57
  • $\begingroup$ A really tall tower on a mountain top and a really, really long string attached to its top... $\endgroup$ Commented Jun 25, 2020 at 8:01

1 Answer 1


If we limit the technology to pre-1700, there are few choices. They all seem to be variations of navigational Backstaff

A Sextant is a more precise and convenient instrument, but unfortunately it was invented only in 1731. The problem of finding direction at this technological level can be solved only through the knowledge of latitude and longitude of both places, and that knowledge requires observation of celestial bodies. Magnetic compass alone is not enough.

Assuming that the coordinates of one of the places is fixed and known, only one other (current) place has to be pinpointed. Once its latitude and longitude is known, an Azimuth can be calculated, which reflects the direction on Earth's surface towards the first place.


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