To Borgia

Illustrissimo Signor mio,

The guns at Piombino are placed too high on the bastions. The parapets elevate the barrels beyond the natural line of fire, and the angle of descent shortens the shot’s reach by a third. The enemy battery below will answer before ours can reply with effect. I measured the slope with quadrant and cord; the deviation is constant at 12 degrees east of true. Correct this by lowering the platforms by one braccio and shifting the embrasures two palmi toward the seaward angle. The stone masons know the cuts; I marked them in red chalk on the south wall this morning.

The twelve culverins you sent from Pisa should be mounted on the lower tier, not the upper. The upper tier is for the lighter falconets, which can traverse the narrower arc. The culverins need the wider field and the direct line to the mole. Place them where the old Genoese guns stood; the foundations are sound and the embrasure widths match.

The powder magazine leaks. The stone vault is sound, but the lime mortar between the keystones has cracked. Rainwater enters at the north joint. I had the garrison engineers scrape the old mortar and repoint with a mix of pozzolana and crushed brick in a 2:1 ratio. They will finish by the 10th of the month. Cost: 24 ducats, paid to Maestro Antonio of Piombino. Receipt attached.

The sentinels report movement along the road from Campiglia. A company of infantry, perhaps 200 men, with two small field pieces. They will arrive within five days if they march at forced pace. The guns, once lowered, will cover their approach from 800 passi. The culverins will reach 1,100 passi with 20-pound shot. The falconets will cover the flanks at 600 passi. The angles are such that no dead ground remains.

Test the alignment at dawn on the 8th. Use the heliotrope I left with the castellan. If the batteries do not converge on the road’s midpoint, adjust the embrasures again. I cannot return before the 12th; the fever returns to my hand and my breath shortens.

The wind here is salt and constant from the southwest. It carries the sound of the sea into the courtyard at night. The gulls cry like men arguing over debt.

Valete,

— L.