Reckoning the cost of digging a canal in ducats
Widths, depth and price per quadretto worked out to a total of 15,187 1/2 ducats for thirty miles.
This page is entirely a pen calculation, with no drawing, of the cost of excavating a canal. Leonardo takes a channel 16 braccia wide at the bottom and 20 at the mouth as, in effect, 18 braccia wide and 4 deep, and prices the digging by the quadretto. Converting the common braccio to the land measure reduces a mile from 3,000 to 2,250 braccia, giving 675 ducats per mile at 4 denari and 506 1/4 at 3 denari, so that thirty miles of digging come to 15,187 1/2 ducats.
On this page
Excavating a canal 18 braccia wide and 4 deep
A canal 16 braccia wide at the bottom and 20 at the mouth is reckoned as 18 braccia wide throughout and 4 braccia deep. The digging alone of a mile is priced at 900 ducats when the quadretti are of the common braccio.
Common braccia converted to land braccia
Taking the mile as 3,000 common braccia turned into land braccia, the note subtracts a quarter to leave 2,250 braccia. At 4 denari the braccio this makes 675 ducats a mile, and at 3 denari the quadretto, 506 1/4.
15,187 1/2 ducats for thirty miles of digging
The reckoning is carried through in ducats and denari to a final total. The excavation of 30 miles of canal is set at 15,187 1/2 ducats.