Put the compass in different corners of the same room, but there is a big deviation between the south and north directions. Why?

When the compass is placed in different areas and different corners, different environments will affect the compass deviation. Another reason is that the magnetic declination of the compass does not mean due south.

magnetic declination of place names

Mohe 11 '

Qiqihar 9 54'

Harbin 9 39'

Changchun 8 53'

Manzhouli 8 4'

Shenyang 7 44'

Lvda 6 35'. Shanghai 4 26'

Taiyuan 4 11'

Baotou 4 3'

Nanjing 4 '

Hefei 3 52'

Zhengzhou 3 5'

Hangzhou 3 5'

Xuchang 3 4' < p

Changsha 2 14'

Ganzhou 2 1'

Hengyang 1 56'

Xiamen 1 5'

Lanzhou 1 44'

Chongqing 1 34'

Zunyi 1 26'

Xining 1 22. 1 5'

Kunming 1 '

Nanning 5'

Zhanjiang 44'

Pingxiang 39'

Haikou 29'

Lhasa 21'

Everest 19' <