Marina Viličić

Research on the Reliability of Mercator’s Map Sclavonia, Croatia, Bosnia cum Dalmatiae parte

This chapter describes further research into Mercator’s map Sclavonia, Croatia, Bosnia cum Dalmatiae parte, which depicts not only present-day Croatia, but Bosnia and Herzegovina, with parts of Slovenia and Serbia. Previous research determined the map projection and scale of the map. A great degree of divergence, which is evident regarding a number of towns on the map in relation to their real, mathematically calculated positions, led us to undertake a more detailed comparison of the geographic contents of Mercator’s map and the actual situation. In this chapter, the positions of river courses and their tributaries are compared, along with the positions of towns along river courses and those on the coast of the Adriatic Sea in the area of Dalmatia and the islands. The results of the research show that Mercator’s map Sclavonia, Croatia, Bosnia cum Dalmatiae parte is a good example of a lovely old map which is, unfortunately, unreliable. It is a reflection of mid-seventeenth century knowledge of the areas depicted and the cartographic capabilities of that era.

The Problem of Double Longitudes on Glavač’s Map

ABSTRACT Stjepan Glavač (1627-1680) produced a map of Croatia dated 1673, on which two meridians appear twice, 40°/51° and 41°/52°. The only written source regarding Glavač’s map is the dedication, which forms an integral part of the map. It does not say which prime meridians Glavač relied on, so in our research we attempted to establish what those prime meridians might have been. We approached the problem of the double longitudes using linear regression, through which we wanted to examine the relation of Glavač’s longitudes to modern values. An essential part of the research was a comparison of Glavač’s map with maps by his predecessors and contemporaries which show approximately the same prime meridians. The maps analysed, with their written values for the longitudes of certain places, indicated that the selection of prime meridians at that time was not entirely reliable. A further problem seemed to be the knowledge of the position of islands chosen as points of departure for longitudes. We concluded that the points of departure for Glavač’s dual longitudes were Palma, one of the Canary Islands, and the islands of Corvo and Flores in the Azores.