Roomul Atlas Journal
Short essays on the history of maps, charts and navigation.
- Why the prime meridian runs through Greenwich
Until 1884 each country measured longitude from its own capital. A conference in Washington settled on one line.
- The longitude problem
Latitude could be read from the stars for centuries. Longitude needed a clock that would run at sea.
- The Blaeu workshop in Amsterdam
For most of the seventeenth century a family firm in Amsterdam set the standard for printed maps.
- Measuring a country with triangles
Surveyors turned one measured line and a great many angles into the first accurate national maps.
- What the Mercator projection does, and why sailors wanted it
A map that stretches the poles was designed so that a ship's constant compass course would be a straight line.
- Ortelius and the first modern atlas
In 1570 a map dealer in Antwerp put uniform sheets between two covers and changed how maps were sold.
- Portolan charts and the sailing directions behind them
Medieval Mediterranean sailors drew their coasts from compass bearings rather than coordinates.
- From lodestone to compass card
How a floating needle became the instrument that every chart and sailing direction depended on.