Nouvelle Carte de la Moitie Meridionale du Globe Terrestre montrant la Variation du Compas, ou le Merveileux accord enchaine des mouvemens regles et ne jamais cessans du vivant pourvoir Magnetique; telles qu'on les a trouvez l'An 1750 (A new map of the southern half of the earth's globe : shewing the variation of the compass, or the marvelous concatenated concurrence of the regular and never ceasing motion of the living magnetick power, as it was found in the year 1750)

• Main Author: Van Ewyk, Nicolaas
• Format: Map
• Language: unknown
• Published: Nicolaas Van Ewyk 1752
• Subjects: Antarc*; Antarctic; Antarctica
• Online Access: https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~340583~90108835; https://media.davidrumsey.com/MediaManager/srvr?mediafile=/Size4/RUMSEY~8~1/195/10997000.jpg

"Rare pair of maps (see our 10998.000 for the Northern Hemisphere) showing the northern and southern hemispheres on a polar projection and illustrating magnetic variation with isogonic lines, based upon the observations of Nicolaas Van Ewyk, a captain in the Dutch East India Company (VOC) in 1750. This is almost certainly the earliest example of isogonic lines covering the entire globe, as well as the first to cover the poles. It improves on the work of other savants like Halley and Van Musschenbroeck. The hemispheres mark longitude in their outer circle. There is another circle just inside this one with numbers from one to twenty, ascending and descending as one travels east to west. These are measurements of magnetic variation; the lines radiating from them are isogonic lines, showing places where that variation is equal. A double line runs through the chart; it splits the variation readings between northwest and northeast, like a geomagnetic prime meridian. On both hemispheres, the magnetic pole is marked. In the north, a letter “N” marks the spot, in Hudson’s Bay. In the south, the pole is marked with a letter “Z” and is located just inside the eastern edge of the Antarctic Circle. These conventions are explained in French and Dutch in the lower corners. The maps were by Nicolas van Ewyk, a captain in the VOC who hoped these maps would be a “very useful light for navigation and physics,” as he states in the maps’ titles. Van Ewyk commanded voyages to the East Indies, making navigational observations as he sailed. The geography of the maps is also of interest. There is no southern continent and Van Diemen’s Land (Tasmania) and New Zealand are just unfinished coast lines, awaiting further exploration. The Australian coastline nearly connects to New Guinea; it is peppered with toponyms based on Dutch interactions over the course of the seventeenth century. The southern hemisphere is covered in isogonic lines, but it is also ringed in several ships’ tracks. These include the 1738-9 voyage of Bouvet de Lozier. On ...