Raising the irrigation from Lake Brivio: a canal scheme
How extending the lake plane to the Tre Corni saves eight miles of excavation
A topographic scheme (letters d, f, h, e, b, a, n, c) sets out a way of raising irrigation from the Lake of Brivio along the course of the river Adda. Leonardo shows that if the plane of the lake is carried the four miles to the Tre Corni, only the short canal e f need be dug, gaining irrigation over four more miles and saving eight miles of the most difficult excavation while watering the land as far as the roots of the mountains. He warns that if the lake were no wider than the fast channel, the current would empty and dry it up. A column of figures at the top records the related calculation.
On this page
Raising the irrigation of Lake Brivio along the Adda
Line ab is the plane of the Lake of Brivio, b c the course of the river Adda, and b d the course of the canal to be made. Carrying the lake plane to the Tre Corni waters the land as far as the roots of the mountains; but if the lake were no wider than the fast channel, the current would empty and dry it.
Saving eight miles of canal excavation
By bringing the lake plane the four miles to the Tre Corni (space b e), only the canal e f need be dug, which gains irrigation over the whole space f d, another four miles. In this way the excavation of eight miles of digging is saved, which is a large part of the most difficult work.
Column of figures
A block of numerals at the top of the sheet records the arithmetic tied to the canal scheme, set out in short columns of figures without accompanying prose.