
Escape Compasses - politelemon
http://www.paratrooper.be/articles/escape-compasses/
======
wallflower
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.

~~~
NikolaeVarius
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.

~~~
jdietrich
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-...](http://silva.se/product/compasses/compasses-
outdoor/compass-metro/)

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°.

------
Luc
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originally made (half-life 1600 years).

~~~
tzs
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](https://imgur.com/4CljfDL)

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

[3] [https://www.sciencefriday.com/educational-
resources/build-a-...](https://www.sciencefriday.com/educational-
resources/build-a-cloud-chamber/)

~~~
helper
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...](https://play.google.com/store/apps/details?id=com.rdklein.radioactivity)

[2]: [https://www.amazon.com/Atomic-Adventures-Islands-
Forgotten-I...](https://www.amazon.com/Atomic-Adventures-Islands-Forgotten-
Isotopic/dp/1681774216)

------
gattilorenz
> _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.

