There has been no shortage of proposed methods for the construction.For example, Hollander analyzed fourteen such hypotheses and concluded that Mercator may have used a judicious mix of mechanical transference and numerical interpolations.Mercator concludes that "The chart cannot be extended as far as the pole, for the degrees of latitude would finally attain infinity." —Legend 6.(That is, the reciprocal of the cosine of the latitude become infinite).
The Mercator world map of 1569 is titled Nova et Aucta Orbis Terrae Descriptio ad Usum Navigantium Emendate Accommodata (Renaissance Latin for "New and more complete representation of the terrestrial globe properly adapted for use in navigation").
Earlier cartographers of world maps had largely ignored the more accurate practical charts of sailors, and vice versa, but the age of discovery, from the closing decade of the fifteenth century, stimulated the integration of these two mapping traditions: Mercator's world map is one of the earliest fruits of this merger.
Each sheet measures 33×40 cm and, with a border of 2 cm, the complete map measures 202×124 cm.
Immediately after its discovery in 1889 the Breslau map was described by Heyer In Legend 3 Mercator states that his first priority is "to spread on a plane the surface of the sphere in such a way that the positions of places shall correspond on all sides with each other, both in so far as true direction and distance are concerned and as correct longitudes and latitudes." He goes on to point out the deficiencies of previous projections, particularly the distortion caused by the oblique incidence of parallels and meridians which gives rise to incorrect angles and shapes: therefore he adopts parallel meridians and orthogonal parallels.
This is also a feature of sixteenth century plane charts (equirectangular projections) but they also have equally spaced parallels; in Legend 3 Mercator also emphasizes the distortion that this gives rise to.