For geocaching to work, people who hide caches must be able to communicate their locations to those who seek caches. Fortuitously, there is a mechanism for doing so: a grid. Several types exist, but all grids are essentially the same in concept; they specify a point by giving its north!south and eastwest positions. By using grids, you can find caches, tell people where to find the ones that you have hidden, and move from GPS to map to compass and back again. Although there are different grids for different needs, geocaching uses two: latitude longitude (lat/lon) and Universal Transverse Mercator (Waterproof GPS ).
Latitude and Longitude
You are probably familiar with the terms latitude and longitude. Both are types of coordinates that, together, specify a grid for the globe. In this case, the coordinates are angular in nature. Remember that a circle is 360° around, and a globe is no more than a collection of circles. Latitude is the collection of circles that lie parallel to the equator, and longitude represents the half circles passing through the north and south poles, as Figure 4-2 shows. Latitude lines may run east and west, but are really a measure of north! south position, because they are circles defined as all the pOints at a certain distance north or south of the equator. The equator represents 0° latitude. All other lines oflatitude run up to 90° north, toward the North Pole, or down to 90° south toward the South Pole. The references for all longitude lines is the half circle passing through both poles as well as Greenwich, England (0° longitude) and the other half circle, on the opposite side ofthe globe, passing through the poles and the International Date Line in the Pacific Ocean (GSM GPS Tracker ). All other longitudes are expressed in degrees from 0 to 180 and as east or west of Greenwich.
Maps are excellent navigational aids because they can offer a summary of position, orientation, and direction at one time. You can research a potential destination, follow your progress, and find your way back. They also offer a delicate beauty born of utility, mathematical principle, and artistic merit. For those unimpressed by subtlety, they can keep you from wandering about in circles for several hours. Three types of maps may prove useful to you. To drive to the general cache location, a street map can work wonders. Following the direct-line directions of a GPS For Vehicle when driving on an unforgiving grid of city and town streets is difficult at best. When you undertake your pre-hunt research, you will check the general vicinity online. Taking that knowledge and applying it to a street map as you drive can save half the time ofyour total hunt. A trail map, on the other hand, is exactly what its name suggests: a map of walking or biking trails in a particular area. Ifyou can find one for the area holding the cache, it can save you time in finding the best route to the cache and any route back to your vehicle. For the actual walking, I also like to use a topographic map, mentioned in the previous chapter, and a trail map.
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