Here is a mystery: I believe that this section
of track
on a turntable at the Railroad Museum illustrates
the four gauges used in India; I know that it shows at least
two (Standard - 1676 mm, and two-foot narrow - 610mm) because
I compared the two-foot gauge to the track holding exhibits
that I knew to be two-foot gauge. The third gauge is Meter (1000 mm),
and the fourth is 2.5-foot narrow, or 762 mm. But I cannot make
the numbers come out right to get all four gauges out of
these four rails. I know that the museum has Standard, Meter,
and two-foot narrow gauge exhibits, but I’m not positive
about 2.5-foot gauge. Note that the center rails on the turntable
don’t line up with the center rails on the fixed track; I assume
that they would if the turntable was rotated 180 degrees.