Titles of Ancient Poems in the Yangtze River (Wen Tianxiang)

The Yangtze River, Tian Xiang, Wen Song

I swam downwind in Beihai for a few days and came back from the head of the Yangtze River.

My heart is a magnet, which doesn't mean that the South won't rest.

Title:

Wen Tianxiang, a national hero, wrote a poem in the Yangtze River, "My heart is a magnet, but it doesn't mean that the south will not rest". The magnet needle stone here is influenced by _ _ _ _ _ _ _ _ _, and its south pole points to _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Answer: geomagnetic field; south