連弩車
The Repeating Crossbow Carriage
禽子再拜再拜曰："敢問適人積土為高，以臨吾城，薪土俱上，以為羊黔，蒙櫓俱前，遂屬之城，兵弩俱上，為之奈何？"子墨子曰：子問羊黔之守邪？羊黔者，將之拙者也，足以勞卒，不足以害城。守為台城，以臨羊黔，左右出巨，各二十尺，行城三十尺，強弩之，技機藉之，奇器口口之，然則羊黔之攻敗矣。
Qin Guli bowed twice and said: 'I venture to ask: if the enemy piles up earth to make high mounds overlooking our city, brings up brushwood and earth together to form an assault ramp, advances with armored shelters covering them, extends the ramp all the way to the city wall, and sends soldiers and crossbowmen up -- what should we do?'
Master Mozi said: You ask about defending against the assault ramp? The assault ramp is the strategy of an incompetent general -- sufficient to exhaust his troops but not sufficient to harm the city. For defense, build an elevated platform on the city wall to overlook the ramp, with projecting bastions extending twenty chi to the left and right, and a mobile wall of thirty chi. Direct strong crossbow fire upon it, deploy counter-siege machines against it, and bring unconventional weapons to bear. The assault ramp attack will then be defeated.
Notes
The 'assault ramp' (羊黔/羊坽) was a common siege technique: building an earthen ramp against the city wall to allow troops to storm the walls from above. The Mohist counter-strategy involves building elevated platforms and projecting bastions to maintain the height advantage.