Hacker News new | comments | ask | show | jobs | submit login
Escape Compasses (paratrooper.be)
81 points by politelemon 7 months ago | hide | past | web | favorite | 26 comments



At times, having a small discreet compass in hand when exiting a subway station in a foreign city has helped me avoid the "this person is a tourist/not from here" behavior by allowing me to proceed confidently out of the subway exit in the right direction. I know that you can use a phone to do this but I think that decreases situational awareness.


I don't usually carry a compass with me in the city but I should. The feeling you described exiting a metro is indeed one of the okay confusing I've felt in my life. But that might be because I usually have a very strong sense of orientation and loosing it is unusual.

That being said, I think it's kind of becoming a dying art to orient yourself by compass and cardinal points. Most people have a hard time thinking in cardinal points and don't seem too interested in fixing this. But that is a shame since directions such as "go right" are too relative to your reference point to eliminate confusion.


A friend of mine used a small compass when he inadvertently found himself in a rough part of a metropolitan city. He had just purchased a zipper-pull compass from an outdoor store and didn't expect to use it in that context, but he swore it saved his life. Apparently it was one of those situations where walking in the wrong direction for a little while can lead you into a maze of miles of dangerous streets.


Any recommendations on a compass? I always hate trying to orient myself via sun in the city, half the time buildings make it annoying to figure out.


The Silva Metro is probably the best option for casual use. Generic button compasses will do in a pinch, but they tend to be quite unreliable. Casio and Suunto make a range of outdoorsy watches with an electronic compass feature, but they look a bit silly.

http://silva.se/product/compasses/compasses-outdoor/compass-...

Satellite dishes can be a very useful directional reference in many urban environments. Here in the UK the overwhelming majority of dishes are aimed at the Astra constellation, so they indicate an azimuth of rougly 155°.


My Pebble Time watch (sadly, no longer in business) has a compass app that I've used a couple of times. Maybe a smartwatch or phone could do the trick?

https://apps.getpebble.com/en_US/application/540f7cafbc27450...


Also satellite dishes point roughly south if you're in the northern hemisphere. (They point towards geostationary satellites which have to be over the equator.) This is a more useful tip in some places than others.


If all you want is north-ish, south-ish, etc., one of the little compasses that attach to a zipper is fine. There are also compass watches. Suunto makes probably the most popular compasses for orienteering but that would be overkill for that application.


>has helped me avoid the "this person is a tourist/not from here" behavior by allowing me to proceed confidently out of the subway exit in the right direction

Because anybody would care how one proceeds? If it's meant to not seem tourist to pickpockets and the like, those can tell anyway...


To clarify, it is more to blend in with the other subway riders and not call attention to yourself so that you look like part of the normal commuter group by knowing where you are going (no backtracking).


I bought a small compass in Akihabara for this reason - my phone was old and unreliable (it would often send me in the completely wrong direction - claiming "north' was really "southeast") and it was a lifesaver. I could look at map, see I need to go east, look at my compass really fast, then go east.

I wore it on my keychain - and I still do! Doesn't come in handy as much since I know where I'm going but it's nice to carry around.


Interesting. I orient myself with the sun. If it's midday, the shadows point southish (southern hemisphere). Mornings westish and evening eastish.


I do the same, without really thinking about it. Changing hemispheres messed me up in terms of direction sense. Even though I consciously knew things were reversed, my "feeling" of which way North was was backwards the whole time I was north of the equator.

(It didn't help that cars were on the opposite side of the road too, so my baked-in "look left when you approach a road" response was suddenly not so helpful.)


Even people that live in the city get disoriented at unfamiliar stops. I know I do, and I take the metro every day. I don’t think it marks you as a foreigner.


Wouldn't a dip needle be better for vertical pathfinding?

https://en.m.wikipedia.org/wiki/Dip_circle


How would that help? The problem is the disorientation one may experience when exiting an unfamiliar underground metro station. A regular compass restores your bearings (literally!) very effectively.


I don't understand how a regular compass will tell you which way the stairs going up are. A dip needle would point towards the stairwell.


It's pretty easy to tell which stairs go up just by looking at them, but it's pretty hard to tell which stairs go north.


I'm guessing you haven't taken the subway in NYC. A lot of times the stairs are only on one side. And the tracks are extremely long and have many trash cans and objects occluding a clear view.


I have read the wikipefia article a few times, but maybe I don't understand what a dip circle does.

My understanding is that it tells you how parallel you are to the magnetic field lines.

I don't see how that helps you find the stairs. All I can see is that if you lay it down on some steps, it will tell you whether it's pointing uphill or downhill.

Is that not correct? Do the magnetic field lines in a tube station somehow point towards the exit rather than the north pole?


Well.. steel or any metal in the ground will distort the field. I don't know if it would point to the stairs but it would definitely show you the least occluded path.


Before you head over to eBay: many of these have radium dots that can be detected by gamma ray detectors at customs offices. The paint may not light up anymore, but the radium is still emitting nearly as strongly as when originally made (half-life 1600 years).


Is there a reasonable way to tell if an old glow in the dark thing uses radium (or some other radioactivity based lighting mechanism) rather than simple phosphorescence, short of finding a Geiger counter?

I've got a Westclox Baby Ben glow in the dark wind-up alarm clock that I've had at least 50 years [1]. I don't think that there is anything I have owned longer. It still works fine, although sometimes it needs to be slapped a little to get it going if it hasn't been used for several years. I still use it as a backup whenever I need an alarm in circumstance where an alarm failure would lead to serious, hard to deal with consequences.

Westclox definitely used radium at one time in their Baby Ben clocks [2], but from what I read they stopped in the early to mid '60s. Mine was bought around the mid '60.

Mine only glows after exposure to bright light, suggesting it is using phosphorescence rather than radioluminescence, and so should be safe, but it would be nice to check.

Would a homemade cloud chamber [3] work?

[1] https://imgur.com/4CljfDL

[2] https://www.youtube.com/watch?v=wp6Ddcc4GAg

[3] https://www.sciencefriday.com/educational-resources/build-a-...


If it only glows after exposure to light it isn't radium.

CMOS sensors can detect gamma particles. If you have an android phone there's an app that actually works (assuming you follow the calibration steps properly)[1]. Apparently Radium mostly emits alpha particles so I'm not sure how effective this would be.

If you are thinking about buying an actual geiger counter make sure to get one with a working probe assembly. A lot of surplus geiger counters are sold without the probe assembly with is the expensive part and the thing that wears out[2]. The probe assembly also needs to be properly calibrated.

[1]: https://play.google.com/store/apps/details?id=com.rdklein.ra...

[2]: https://www.amazon.com/Atomic-Adventures-Islands-Forgotten-I...


Also beware that radium decays to radon. Some watch collectors have to worry about this.


> Later war models had a top that had a reverse thread, so to unscrew them, you had to twist the other way. This was done after the Germans were known to have found out about the existence of this type of compass.

I'm amazed by the simplicity of the solution, it's a brilliant idea. Same for the buttons sewn on the uniform, and the other everyday objects that turn into a compass, I love how they are hiding in plain sight.




Applications are open for YC Summer 2019

Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact

Search: