Think of a map as being a two-dimensional representation of a three-dimensional world, or in somewhat simpler terms, a sort of bird’s eye-view of the earth below.
Then think of the map as being part of a system, one incorporating the use of a compass. Understanding the mathematical science involved in using the two together will go a long way to shortening the distance between where you are and where you want to go.
Last week we got into the science behind a compass and how compasses work on the principal of magnetic attraction, the difference between magnetic north (the direction the north end of a compass needle points) and true north, and how degrees of declination have to be added when determining direction of travel.
Maps are drawings based on latitude and longitude lines.
Latitude lines run east and west and measure the distance in degrees north or south from the equator (0° latitude). Longitude lines run north and south intersecting at the geographic poles. Longitude lines measure the distance in degrees east and west from the prime meridian which runs through Greenwich, England.
The grid created by latitude and longitude lines allows us to calculate an exact point using these lines as coordinates. Topographic map use lines called contour lines to simulate the three-dimensional topography of the land on a two-dimensional map.
Maps are drawn to scale in a way that more easily depicts given areas on a manageable-sized area of view. A scale of 1:25,000 means that a distance of one centimetre on the map represents 250 meters on land. Maps are drawn on a variety of scales such as 1:40,000, 1:50,000 or smaller. The scale is shown in the margin or legend on the side of almost all maps.
Using a map in conjunction with a compass allows one to determine even more accurately a means to getting from one point to another.
There are people who have even gone so far as to make a sport out of using a map and compass. It is called orienteering which, according to Wikipedia, is a family of sports that requires navigational skills using a map and compass to navigate from point to point in diverse and usually unfamiliar terrain, and normally moving at speed. Participants are given a topographical map, usually a specially prepared orienteering map, which they use to find control points. Originally, a training exercise in land navigation for the military, orienteering is now any sport that involves racing against a clock, and requires navigation using a map and/or compass.
With the advent of GPS (Global Positioning Systems), which is a space-based satellite navigation system that provides location and time information in all weather, anywhere on or near Earth, we now have a multitude of electronic devices and mobile apps (software) for one’s cellphone which will do just everything (and more) that we’ve been discussing over the past two weeks.
Like most electronic devices nowadays, one does not necessarily have to know or understand the scientific theory behind the intended use of the device. All you have to do is turn the thing on and let the electronic brain inside take over.
I do have to say at this point that I have become totally dependant upon my vehicle’s GPS unit to navigate my way around when I go to the big city. Not only can I get lost driving around the block but, as anyone who has ever taken a wrong turn knows, it can take an hour to get back to where you started.
That being said, GPS units are not infallible.
The bottom line is that, while electronic devices and apps may make life simpler, having a basic knowledge and understanding of how to use a map and compass can provide, not only a bit of sport but also a sense of security when venturing into the great outdoors – especially when your GPS unit or cell phone’s batteries are dead.
