Expert: Marc Ebelini - 1/10/2005

Question
I want to read compass for example: 76'w and what does it mean of longtitude and lattitude. what does it mean of lat 0.1

Answer
Let's not confuse compass heading with Lat & Lon. 76 degrees means just that. Magnetic north is 76 degrees from your heading. This reading must also consider your local variation and compass deviation. Here in Florida there is a 2 degree error that must be used in your calculations to find true north. The lines of longitudes run from true north to true south "0" starts in England and goes west so 81 degress west would place you in Florida. The latitudes start at the equator and the numbers with N equal north of the equator and S below. Since I am north of the equator I would be 81W 27N. These are course numbers. The actual position would have the degrees, minutes and seconds to get the final resolution.
Laying out the earth this way allows me to drive to my home with the GPS to within twenty feet of my actual location on earth. GPS has made the use of a compass worthless now because it does all the work for you. Converting compass readings to achieve your true path on earth became complex when you needed to constantly up date your compass for deviation and variations.