Ciclo CIX

Illustrissimo Signor mio,

I write from the worksite at Romorantin, where the canal meets the old stone wall and the earth has begun to speak truths the architects did not wish to hear.

The slope of the rampart on the eastern approach — the one we discussed in Imola, the one you ordered built at the angle of thirty degrees — it is wrong. Not in the drawing. The drawing is correct. The masons have laid the courses too flat, perhaps two degrees less than specified, perhaps three. I measured with the quadrant this morning, before the fog lifted, and the batter is insufficient. A cannonball striking that face will not glance; it will bite. The wall will hold for the first impact, perhaps the second. Then the stones will begin to shift inward, and the whole face will collapse like a man leaning too far forward.

I have ordered them to dismantle fourteen courses and lay them again. This costs three days. The lime must cure. I told the master mason this and he looked at me as though I had asked him to unmake the sun. But it will be done.

The canal itself. You asked whether it could be dammed to flood the approach from the north. It can. Here — I mark it on the sheet I send folded within this letter — there is a narrow place, stretto, where the banks rise naturally and the bed is firm clay rather than sand. A timber dam with an iron gate, operable from the wall, would hold back sufficient water to make the ground impassable for a column of men. Not for horses alone — horses will find the firm places — but for artillery, for supply wagons, for the slow heavy things an army cannot abandon.

The cost: eight hundred scudi for timber and iron, perhaps one thousand if the iron must be brought from Tours. Six weeks of labor. I have spoken to a carpenter here, a man who built the mill at Blois, and he says four weeks if the weather holds. I do not trust carpenters’ timelines. I say six.

The artillery placement on the southern tower — I walked the wall again yesterday and counted paces, as I did at Cesena. The tower covers the road approaching from the south but leaves a dead ground of perhaps two hundred paces at the base of the wall to the southeast, where the ground falls into a depression. An enemy could assemble there under cover and approach the wall with ladders before the guns could depress sufficiently. I propose a small spur, a tenaglia, extending from the southeast corner of the tower. Fifteen paces long, eight paces wide, mounting two falconets. This would sweep the depression and crossfire with the main battery.

The spur costs less than the dam. Perhaps three hundred scudi. Two weeks.

I do not know if you intend to garrison this place through the winter. If you do, the rampart must be corrected regardless. If you do not, the dam is wasted money and the spur is a vanity. I write these things because you hired me to see them, not because I presume to know your intentions.

The hand is worse this month. The letters lean. You will forgive the script.

I remain, as ever, your servant in these matters,

Leonardo

Written at Romorantin, this day the twenty-eighth of May, in the year 1526, by my own trembling hand.