A man firing three Fei Cui Zha Pao, from 'Wu Bei Zhi (《武備志》)'.
Fei Cui Zha Pao (飛摧炸砲, lit. 'Flying destroyer explosive cannon') is a iron bombard, possibly a Wan Kou Chong (碗口銃, lit. 'Bowl-muzzle gun'), that is used to fire cast iron shells. The shells are filled with small caltrops, which serve as fragmentation during detonation but will remain on the ground to deter enemy advance afterward. The bombard is typically loaded with multiple shells, allowing it to cover a large area (the shells will further spread the caltrops over an even larger area).
Leonardo da Vinci's bombard, from 'Codice Atlantico'.
As a side note, I personally find that Fei Cui Zha Pao bears a little similarities to the bombards designed by Leonardo da Vinci. Coincidence?
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