Wubei Zhi (Vol. 48)

Wubei Zhi, Volume 120

For every battlement, construct a wooden frame according to the standard pattern. If the enemy attacks the city, hang damp felt mattresses original: 濕氈褥 wet felt bedrolls/mattresses over the frame. The soldiers guarding the battlements may then throw stones and roll logs original: 滾木 rolling logs from the frame to repel the enemy. This also serves as a defense against downward-firing arrows, ensuring they cannot harm the men stationed above.