The main features of the map were placed on the grid made by the inner circle which is centered south of Genoa.

The circle is divided into sixteen equal parts. Rhumb lines connect to the points on the circle and provide a grid.

Rumb lines on the circle

The rhumb lines on the map could be followed to navigate a vessel at sea; the grid made from them could be used to copy this portolan chart. [For more detailed circles in separate windows, click on the images.]

navigating on the rhumb

The five scales of distance could be used to determine distance along the rhumbs.

scale sample

One compass rose is located in southwestern Africa; a second is found in the northeastern part of the map.

compass rose
compass rose

Can you find the compass roses and the scale on the Large 1489 Chart? Young navigator link

magnifying glass Under the Magnifying Glass

The 1489 Canepa


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