The magnetic needle is seriously deflected from its normal position when it is under the influence of external attractive forces. Such a disturbing influence is known as local attraction. The term is also used to amount of deviation of the needle form its normal position.
If the needle is perfectly balanced before magnetization, it remains in horizontal position. But it will not remain in the same position after it is magnetized, on account of the magnetic influence of the earth. It will be inclined downwards towards the pole. The inclination of the needle with the horizontal is known as dip of the needle. The amount of dip is not constant, but varies in different parts of the earth. It is 0 degree at the equator and 90 degree at the magnetic poles.
The magnetic meridian at a place does not coincide with the true meridian at the place except in few places. The horizontal angle which the magnetic meridian makes with the true meridian is known as magnetic declination or simply declination of the needle.