Surveying the Brivio canal to the Travaglia mill
Levels, fall and locks — with a caisson, sluice-gate and plan of the works
Leonardo records a survey of the irrigation canal from Brivio to the mill of the Travaglia: 2794 trabocchi (11176 braccia), more than three and two-thirds miles, with the canal found 57 braccia above the surface of the Adda and allowing two inches of fall per hundred trabocchi at the point chosen for the canal mouth. Accompanying figures show a caisson with coarse cloth packed between framework, water and bed to still the water behind a dam, a one-piece sluice-gate, and a plan and panorama of the works naming the Travaglia mill, the Adda and Santa Maria. A multiplication (2794 x 4) is worked out at the top.
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Survey of length and fall to the Travaglia mill
From the start of the Brivio canal to the Travaglia mill is 2794 trabocchi, that is 11176 braccia, more than three and two-thirds miles. The canal is found 57 braccia above the surface of the Adda, allowing two inches of fall per hundred trabocchi, and at that site the mouth of the canal is planned.
Caisson and dam to still the water
The bed is to be raised a crossbow-shot below the sluice so the water backs up and stands without current, with coarse cloth set between the framework and the water and between the water and the bed; a hollow is to be cut in the Tre Corni to seat the wall that closes the water.
Plan and panorama of the works
A plan and a panorama lay out the works to be carried out, labelling the irrigation canal, the Travaglia mill, the Adda and the Rocchetta at Santa Maria; in excavating the lock the earth is to be counterweighted with a box of water.
Converting trabocchi to braccia
At the top a multiplication works the conversion of the surveyed length, multiplying 2794 by 4 to reach 11178, the figure of braccia used in the survey note.