you need
  • - pocket calculator.
begin with, that of all the measures of length, existing in different countries, to the arc of degrees, minutes and seconds of the Earth's surface most tied nautical mile.She originally conceived in this way.In fact, the nautical mile - is one minute of arc of a meridian.
With the introduction of the international measures of length - meter, it was found that in the nautical mile of 1852.4.Thus, it turns out that one minute of arc of the meridian on any map - whether sea, land - one kilometer, eight hundred fifty two meters and forty centimeters.In one degrees respectively: 1852.4 x 60 = 111,144 meters, or 111 km, 144 m.
on charts navigators determine the rest of the way, or passed, the distance to the object using a s
imple meter.In the same way you can do, working with the map, say, roads.To do this, put a needle gauge in the extreme points of the measured distance, and then attach to the frame of the card to the line, broken into degrees , minutes and seconds.It is important for the accuracy of the distance to take readings on the same parallel.Because when you transfer to a plane meridians and parallels undergo natural distortion (Mercator projection).The closer to the poles, the minute line segment, for example, will be longer.And if the distance shot at a southern latitude, to measure the degree to map grid higher readings in miles will be too low, and vice versa.
Keeping in mind that you probably operate a small distance, it is useful to know the fullness of a second arc of the meridian.This information is useful to have and for hikers, and even in everyday situations.One second the result is again simple arithmetic will have: 1852.4: 60 = 30.87, approximately 31 meters.