Treatise on Armament Technology, Volume 114

Military Equipment: Defense of Fortifications

...the height [of the tower] should be ten feet original: 丈 zhang, approximately 3.3 meters. higher than the wall, and the top should taper to a square of twenty feet. The structure should extend straight out to the east and west, with crenellations original: 睥睨 pini, the low, notched wall or battlement used for looking out and firing upon attackers. reaching a height of three feet and then stopping.

Vertical wooden pillars of over two feet should be erected, with horizontal beams added on top to form another wall about a foot high. The middle of this structure is hollow, with wooden shutters placed on the sides. On the outside, there are protective eaves, while on the inside, rotating levers are added so that the shutters can be opened or closed at our will.

This method can be used for the wooden parapets original: 女墻 nuqiang, literally "woman's wall," a low protective wall on top of a rampart. that screen the city; it is even more convenient.

When the enemy original: 虜 lu, a derogatory term for invaders. aims their arrows original: 矢 shi. at one spot, we simply open a shutter at another. The reason shutters are usually vulnerable to aimed fire is that the opening is typically fixed in one place. If the shutters are opened unpredictably, then we need not fear their aim.

This design is specifically intended for the use of firearms original: 發火噐 fahuoji, any weapon using gunpowder, such as fire-arrows or early muskets. and arrows. As for catapult stones original: 礮石 paoshi., they pass through the indented gaps in the wall; one does not need to stare out or calculate their trajectory from the shutters. Once the watchtower is completed, the limitations of these shutters must be discussed.

If the walls are not high and the shutters are made too thin, they will not withstand the impact during an attack. With battering rams and flying stones constantly coming and going, defending oneself cannot be sustained for long. Once the suspended stones and suspended logs original: 縣石縣木 xuanshi xuanmu, heavy defensive weights hung from the wall to be dropped on climbers. are released together, if they fall down, then...

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