So no data then?
If you understood map construction then you wouldn't ask that question. Maps themselves are nothing but compilations of data represented by spatial relationships. By looking at a map that has the Gulf Stream Current, you are looking at the embodiment of data which indicated that such a body existed, and that it has a measurable spacial relation to everything else on that map.
Anyway, this is how you make a map. You start with a sheet of paper or a program, and using GPS or calculating distances to landmarks and boundaries using old school triangulation surveying techniques, you plot points on a grid.
These points are your data. As a geologist I've had plenty of experience making maps, so I can confidently tell you that the data doesn't translate to a forum board, it translates to a picture... IE, a map. Even if we did it using multiple sheets of overlaying tracing paper, that sort of thing can't be stuck on a forum board. At the same time, I don't think the hundreds of thousands of lines of raw code from the ArcGIS program that geographers use would mean much to you. But you obviously don't want me to show you maps, you want the data behind them, which as I just explained is a completely nonsensical request.
Nowadays we use digital satellite images in combination with other types of computer generated maps (zoning maps, street maps, precipitation maps, etc) and layer them ontop of each other like tracing paper and assign specific information using lines, points or polygons in order to make maps with database-like properties more useful across all sorts of disciplines. But that's neither here nor there.
The only other way for us to show you that the latitude lines of the Tropics have the same distance would involve using a private plane and flying along those lines. You are more than welcome to do this -- since FE'rs don't actually have a map that they can use to base calculations on.