Theater of Machines, Volume 3

I will first describe various types of mill-works, how they may be used in different places and at all times without water. For some can be prepared and used in places where, either because of the height, there is no water at all, or the waters have been completely dried up by great heat in hot or arid summers, or have been completely frozen over in hard winters.

Others serve in the opposite case, where the waters are far too great and therefore swamp the mill-work entirely.

Some are also useful, indeed necessary, in sieges of fortresses, where the enemy has cut off the water, or has otherwise hindered the exit and entrance in such a way