The representation of tides on old maps
Cartographica Helvetica 24 (2001) 29–35
The old seafarers already knew that at high tide the moon could always be observed in more or less the same position in the skies, and that with respect to the phases of the moon, high tide always occurred at about the same time of day. The tidal charts in the Catalonian World Atlas, the dial-like drawings by Brouscon and D'Argentré, as well as the sketches by De Hooghe were all based on these two pieces of information. Each of these three authors succeeded in representing tidal observations in a practical form. A comparison of the navigation maps investigated in this article with modern observations, especially the information about tides, provides interesting indications as to their application and use.