Rows of Diggers and the Rising Price of the Ditch by Depth
Earth relayed by two or three men; price climbs from 5 to 16 1/2, mean 12 lire
Continuing from folio 10 recto, Leonardo describes how rows of diggers relay the spoil out of a deep ditch: earth from the central 8 braccia is handled by three men, other earth by two, the rest by one, with two extra rows on the bank spreading it so it does not fall back. He then reasons out the labor cost by depth: the first canne near the embankment merit 5 lire, the second (handled twice) 8, so he takes the mean of 7 1/2 lire per canna in the first 4 braccia; since each degree of depth adds 3 lire, the lowest reaches 16 1/2, and the mean over the depth comes to 12 lire. Marginal columns of arithmetic and small diagrams of ranked workers support the reasoning.
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Relaying spoil out of a deep ditch
Two rows dig and cast their earth clear of the ditch, two more pass earth from the center to them, and two more relay from the very middle, so that the central 8 braccia of spoil is handled by three men in turn. Two further rows on the bank spread it so it cannot slide back in.
Price per canna rising with depth
First canne near the bank merit 5 lire; the second, being handled twice, merit 8 (not 10, since the first diggers already did the loosening). Taking means, he sets 7 1/2 lire for the first 4 braccia and, with 3 lire added per degree down to 16 1/2, arrives at 12 lire.
Marginal calculation columns
A stacked reckoning runs down the left margin: 272, 640, 1088, 1632 building to 174080, with a division against 2720 and the product 2720 by 64 giving 10880 and 16320 summed back to 174080.
Diagrams of ranked workers
Small framed sketches at the left show rows of little figures set in ranks within the ditch, illustrating the filari (files) of men who dig and pass the earth outward.