LOCAL ATTRACTION

A freely suspended and accurately balanced magnetic needle is expected to indicate magnetic meridian. However, local objects such as electric wires and objects of steel attract magnetic needle towards themselves. So, needle is forced to indicate slightly different direction. This type of disturbance is called local attraction. The lists of materials which cause local attraction are following:

(i), iron poles, steel structures, rails, electric poles and wires,

(ii) Magnetic rock or iron ore

(iii) Chain, arrows, hammer, clearing axe etc.

(iv) Key bunch, knife, iron buttons, steel rimmed spectacles, and Surveyor are expected to take care to ignore local attractions listed in (iii) and (iv) above.