Analysing the projection of the Mercator map of 1569 with regard to the geometric construction method

The method with which the Mercator projection can be created in a purely geometrically correct manner was reconstructed. The projection in the Mercator map of 1569 was analysed using this reconstructed method. The comparison with the mathematically calculated network of degrees showed that Mercator very probably used this method. There are objective and pragmatic reasons for the differences between the degree network of Mercator's map and the mathematically calculated degree network or the degree network created using the reconstructed geometric method. The objective reasons include the very large extent of the map and its composition from different sheets. The pragmatic reason lies primarily in the fact that Mercator only wanted to use the wall map to demonstrate the rectilinear representation of the rhumb lines in the projection he had invented. He did not need a highly precise realisation of the geometric method for this. The deviation of the projection in Mercator's map from the fairly precise application of the geometric method is therefore not due to the fact that Mercator used a different method to determine the distances between the circles of latitude.