Hese Problems are presented by the Learned and Industrious Nicolaus Mercator, for the advancing of that Excellent and Beneficial Science, Navigation, as follows:

The line of Artificial Tangents, or the Logarithmical Tangent-line, beginning at 45 deg. and taking every half degree for a whole one, is found to agree pretty near with the Meridian-line of the Sea-Charte; they both growing, as it were, after the same Proportion. But the Table of Meridional degrees being calculated only to every Sexagesimal minute of a degree, shews some small difference from the said Logarithmical Tangent-line. Hence it may be doubted, whether that difference do not arise from that little errour, which is committed by calculating the Table of Meridional degrees only to every minute.