Latitude identify a north/south reference and longitude identify a east/west reference for any point of the surface of the earth. Latitude or longitude can be display as degrees/minutes/seconds or as fractional degrees. For example, the longitude "34° 55' 25? W equates to -34.92361 (34+55/60+25/3600). A minus sign denotes that a latitude is south or a longitude is west.

Determining the approximate latitude has always been possible by mapping the calender to the position of the Sun during the day and stars at night. However, determining longitude was a more difficult task. John Harrison, a clock maker in the early 1700s, determined the first useful method for determining latitude for sailing. His approach depended on syncronizing two clocks at a know longitude at noon (sun above head) and resetting one of the clocks every day at noon. The difference between the two clocks identified the time zone change and would provide a fairly accurate estimate of the longitude each day.

The following program is useful for calculating the general travel distances between various sites. The latitude and longitude numbers can be plugged into to most gps.

After downloading the file, extract both files to a new directory. Edit the MyPOI.txt file to add as many new points of interest as needed. The format is: latitude space longitude space "Name". When the MyPOI.txt file is ready, just double click on the MyPOI.bat file. A file named "MyPOI.ov2" will be created. This file (renamed if needed) should be placed in the Tom Tom map directory. Restart the gps device and the new POIs should be available.

Additional information is available:

1. Acura Versus TomTom One
   
2. Traffic Camera POIs
   
3. Poi Tool
   
4. GPSBabel
   
5. PDA to GPS cables