There was recently a short debate about a map purported to show Alaska. It was interesting because, although it did not show Alaska at all, it did show what that cartographer was thinking at the time, and how this was expressed.
The initial assertion was that this map was of North America, with Alaska to the left of the map (being blown upon by the wind.)
Note especially, the left edge of the map is double ruled and the land goes up to the inner of the two lines.
This was actually a section of a larger map, of the northern hemisphere, and the full map tells a different story.
This is the idea behind the map
As you can see, the original map is divided into three arcs, each of 120 degrees, with two filled with map data and the third arc containing decorative images rather than oceans / islands.
The arcs are divided by double rules, the inner of each meeting at the centre point on the north pole, where they are joined by the single rule through the centre of the two mapped arcs.
Also radiating from this point are lines of longitude, if you count the lines, you will identify that there are 36 sections in the two mapped arcs, eighteen each side.
These are actually ten degree sections and the whole 36 sections make up the 360 degrees of the circle.
The way to read this projection, is to cut out the decorative arc and join the +180 longitude to the -180 degree longitude, as shown in the picture.
A simpler copy of the map is here.
Here it is turned into a cone projection.
NB This is a mirror of a page originally hosted by Freeweb, courtesy of the author.