human
But, of course, the variation has changed, Captain Doane. Have you allowed for the change in variation for half a century! That should make a grave difference. Why, as I understand it, who am no navigator, the variation was not so definitely and accurately known in those days as now.
gpt
Latitude was latitude, and longitude was longitude, would be the captain's retort.
human
Variation and deviation are used in setting courses and estimating dead reckoning.