Talk:Gyrotheodolite

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Operation

I am confused by the way the term 'meridian' is used here. The definitions referred to in the text are:

"Meridian (astronomy), imaginary circle in a plane perpendicular to the planes of the celestial equator and horizon.

Meridian (geography), an imaginary arc on the Earth's surface from the North Pole to the South Pole".

Clearly there are many such circles or arcs, so to speak of 'the meridian' as if there were just one is meaningless. I suppose that 'the meridian passing through the point of observation' is intended, in which case the phrase 'due North' (or 'due South') can be substituted in most cases, giving a clearer meaning. Is this correct, or what is intended ? Will someone who understands this please edit the text to make it clearer ? Possibly this could be resolved by giving a definition for 'meridian' which is compatible with the usage. g4oep — Preceding unsigned comment added by 77.96.58.212 (talk) 07:38, 1 August 2015 (UTC)[reply]