1. Application of the local magnetic variation to the recorded heading will give the true heading.

2. This may explain some of the magnetic variations that mystified old-time sailors.

3. For example earthquake inspection station magnetic variation curve record and so on.

4. The possibility of accomplishing the automatic modification of magnetic variation in a simple way is analysed for the medium-range and short-range aircraft in our country.

5. Magnetic heading , the compass heading corrected for magnetic deviation but not magnetic variation; thus, the heading relative to magnetic north.

6. Compass heading or compass course, before correction for magnetic deviation or magnetic variation.

7. Because there is a continuous small change of direction of lines of magnetic force over the surface of the earth , magnetic variation at most locations is not constant over long periods of time.

8. Two-dimensional model by magnetotelluric data has been obtained and compared with the results by magnetic variation analysis.

9. The problems to be solved in transplanting the automatic modification program of magnetic variation and the methods for solving them are discussed.