釋鑑稽古略續集 3.106

3.106

武剛車　衛青所制。長一丈五尺。高六尺五寸。上開小窓下留銃眼。前後左右橫排鎗頭。每車前後占地五步。若用一千輛。一面二百五十。約長四里。內藏軍馬糧草輜重。以此禦敵。使馬不得衝陣。箭不得傷人　所謂備有脚之城運無糧之馬云。

The Wugang Chariot was devised by Wei Qing. It was one zhang and five chi long, and six chi and five cun high. Above, small windows were opened; below, gun ports were left. Across the front, rear, left, and right, spearheads were arrayed. Each chariot occupied a space of five paces front and back. If one thousand chariots were used, with two hundred and fifty on each flank, they would extend roughly four li. Inside, troops, horses, provisions, and baggage could be concealed. Using these to resist the enemy, horses could not breach the battle array, and arrows could not harm the men. This was what was known as "providing castles with feet and transporting horses without fodder."