Historic Question a/b Early Modern Maps & Their Grid Systems

[Will Phillips]

I've been looking at the maps in the Mercator and Ortellius atlases from the late 16th century and am stumped. What were the grids in the borders supposed to be lining up to?

It wasn't the mileage to scale.

I don't think it was to any latitudinal or longitudinal coordinates.

Has anyone come across an answer or hypothesis to this?

Reference images:

https://commons.wikimedia.org/wiki/F...cator)_181.jpg

https://commons.wikimedia.org/wiki/F...ris_(1594).jpg

[Tenia]

I don't think it was to any latitudinal or longitudinal coordinates.

Has anyone come across an answer or hypothesis to this?

Reference images:

https://commons.wikimedia.org/wiki/F...cator)_181.jpg

https://commons.wikimedia.org/wiki/F...ris_(1594).jpg

Hi,
They are. Subdivisions of latitudes/longitudes degrees were usually shown in the sexagesimal system, here each of a six subdivision of a degree represent 10 minutes, this explain the 10, 20, 30.. markers.
For longitude, on the Mercator's world map of 1569 the prime meridian was traced throught the Cape Verde Islands, I think the same location is used on thses maps.
Btw, nice maps !

[Will Phillips]

Hi,
They are. Subdivisions of latitudes/longitudes degrees were usually shown in the sexagesimal system, here each of a six subdivision of a degree represent 10 minutes, this explain the 10, 20, 30.. markers.
For longitude, on the Mercator's world map of 1569 the prime meridian was traced throught the Cape Verde Islands, I think the same location is used on thses maps.

Great insight - I was unaware of this!

I'm going to be embarking on a historical map in this style and feel the grid is an important element. This will help me know where and what to research.

[Hai-Etlik]

Here's a tutorial on setting up a fairly simple large scale lat-lon graticule like in these maps https://www.cartographersguild.com/s...ad.php?t=16284