When putting several pieces of the yard long rail together, it is better not
to actually solder or braze the lengths together but rather just provide
electrical connections between the rails with loops of wire.
The reason for this is that the layout expands and contracts a lot over the
years and having a solid piece of rail many yards long will make for
difficulties with kinking and so forth of the track. Better to allow the
rails to move about a bit and that will allow the track to stay where it
belongs.
If you're laying your own rail, butt soldering with silver (5% or so silver)
solder will do fairly well in place although working a piece of metal under
the rail for additional support will help.

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Why isn't there an Ozone Hole at the NORTH Pole?