Gerardus Mercator was a sixteenth century Belgian cartographer. In 1569 he created a world map based on straight lines of contstant course known as rhumb lines. He successfully presented a three dimensional object (the world) on a two dimension piece of paper. For the mathematical minded amongst you its a line that creates an arc on a constant course – I tend to think of it as cutting the world into sections straight through the middle of the planet like so many slices of cake at a constant angle (its not a right angle) but I have the feeling that I have horribly over simplified and may have become fixated on the cake part of the equation…but you get the gist.

Essentially Mercator used the rhumb lines which were constant to draw his charts and maps. He imagined the world, or a chart, as a piece of paper which was rolled into a scroll. This enabled him to link all the lines of latitude (east west lines) that we imagine going around the world. So far so good and on a small scale it works well. But a problem arises because the world is not a cylinder – it’s a sphere. This means that the lines of longitude (the north south lines) are distorted and if you draw countries based on the straightened out lines the countries at the top of the map like Antartica and Siberia look much bigger than they really are unless you draw the segments so that the top of the world looks like a series of fingers with white paper between them – which isn’t great if you’re trying to navigate somewhere. So having ruled that option out the Mercator projection makes Greenland looks huge – bigger than Africa and that folks is just not true! But Mercator was creating charts for sailors – the oceans needed to be right for them to make navigational decisions not so they could compare the relative size of land masses. Nor does it help that the world is ‘Old World’ centric – the sailors were setting off from the known world into the New World. Basically a world map based on Mercator Projections sees its priorities through sixteenth century eyes.

Essentially, anything past 70degrees latitude isn’t quite the right shape on a map created using Mercator’s projection. Corrections were made even in the sixteenth century but we’re not going there today because that’s more than enough for my brain to cope with in one go. Suffice it to say at the time it was an excellent step forward because it made navigation by mathematical means far easier.

Robert Dudley, calling himself the Duke of Northumberland and the Earl of Warwick was the first Englishman to create an atlas of the sea using mercator’s projections. It was published in 1646-1647 in Florence. It contained more than 100 beautifully engraved maps.