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Perhaps I can squeeze one last drop of juice out of Robert Eno's search for
electrical wire that would remain flexible down to -40 degrees, to
illuminate his sextant. Someone suggested he should make sure the wire was
fully tinned.

I have no doubt of the virtues of tinned copper wire in a marine
environment. Untinned copper wire (especially flexible multistrand) gets
attacked quickly in salt air, goes black, and won't take solder thereafter.
Avoid it.

But down at -40 degrees? That reminds me of the story I heard about
Napoleon's retreat from Moscow. He had issued his troops with campaign
medals which were made of tin. As I remember it, tin has two allotropes,
its crystal structure changing from one form to the other at such low
temperatures. This change causes the metal to crumble. When besieging
Moscow, Napoleon's troops found their prized medals falling apart, which
added sufficiently to their general demotivation caused by cold and hunger
that they decided to turn round and go home. The behaviour of tin at low
temperature had a significant effect on the course of European history.

I wouldn't wish Robert Eno to suffer in the same way that Napoleon did.

George.


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