# Re: OT Re: Constructed maps

From: | Michael Poxon <mike@...> |

Date: | Friday, January 11, 2008, 22:11 |

I have some formulae for drawing (essentially) latitude and longitude
lines,�with appropriate convergence near the poles.�But it may actually be
easier to simply get a tape measure and measure from�one pole to the other on
the globe.�1) divide this distance by 18 (i.e., one pole to the other, not
including�the pole you're measuring from, in order not to have to divide by
19, since�the equator is common to both N and S!) for the latitude
lines.�2) Mark lines at these distances from N to S on your globe, as long as
they�are all on the same meridian. This will give you basically
your"Greenwich"�meridian.�3) Find the circumference of the globe and divide
that by a nice convenient�number like 24. That gives you each "time zone",
i.e., each 15° meridian AT�THE EQUATOR!�4) Use the tape measure to draw
lines from the equator to each pole. Thus�you have your longitude lines. (The
hard bit!)�5) Just join up each latitude mark with the next one R or L on the
same�parallel. Thus you have your latitude lines.��It sounds involved but
it isn't really. It's just an algorithm after all,�and probably easier than
writing a program or spreadsheet - the formulae are�pretty nasty if you don't
like 3-dimensional trigonometry!�Mike�