Fortress Design: The Castellan's Total Surveillance
Sections and a circular plan with defensive maxims, water works and calculations
Dense mirror-script notes and drawings set out an ideal fortress in which the castellan controls every point. Vaulted casemates and an enclosure are drawn in section across the top, while a large circular fortress plan on the right is ruled with the radiating trajectories of gunfire. The text prescribes isolating the garrison under three captains, flooding mines, drawing water from a central bored well, and shaping the walls so that fired balls rebound onto attackers; columns of arithmetic and a numbered list of 1 to 15 run down the margins. Further untranscribed writing is present elsewhere on the sheet.
On this page
The castellan sees and hears everyone unseen
The garrison-men (provvigionati) cannot assail the castellan, who at every moment can see and hear their discussions and counsels without himself being seen. A single sentinel, unmoving, watches the whole castle within and without and is changed every three hours, so that no enemy and no garrison-man can hide anywhere without being observed.
Central well and rebounding shot
A bored well set in the middle of the fortress can supply water to all the ditches at the castellan's request. The mantlet recoils with the ball and returns to its place, and many shots are so contrived that the balls rebound back upon the enemies to their great harm.
Flooded tunnels linking the enclosures
Tunnels beneath the waters let one enclosure relieve another, but none may lead into the keep; the keep's own tunnel is to run above all the other enclosures. All mines can be flooded singly or together and as easily emptied.
Fortress and casemates drawn in section
Along the top of the sheet the fortress and its enclosure (procinto) are shown in section as a range of vaulted, arcaded casemates, with an advanced outwork sketched at the upper left. The letter a marks the castellan's private passage through the structure.
Marginal calculations and a counting column
At the right are columns of arithmetical operations working with figures such as 400, 100 and fractions like 14 2/7 and 42 6/7, with a boxed 400 higher up. Down the left margin the numbers 1 to 15 are listed in a column.