1010.
OF THE CANAL OF MARTESANA.
By making the canal of Martesana the water of the Adda is greatly diminished by its distribution over many districts for the irrigation of the fields. A remedy for this would be to make several little channels, since the water drunk up by the earth is of no more use to any one, nor mischief neither, because it is taken from no one; and by making these channels the water which before was lost returns again and is once more serviceable and useful to men.
[Footnote: "el navilio di Martagano" is also mentioned in a note written in red chalk, MS. H2 17a Leonardo has, as it seems, little to do with Lodovico il Moro's scheme to render this canal navigable. The canal had been made in 1460 by Bertonino da Novara. Il Moro issued his degree in 1493, but Leonardo's notes about this canal were, with the exception of one (No. 1343), written about sixteen years later.]
1011.
No canal which is fed by a river can be permanent if the river whence it originates is not wholly closed up, like the canal of Martesana which is fed by the Ticino.
1012.
>From the beginning of the canal to the mill.
>From the beginning of the canal of Brivio to the mill of Travaglia is 2794 trabochi, that is 11176 braccia, which is more than 3 miles and two thirds; and here the canal is 57 braccia higher than the surface of the water of the Adda, giving a fall of two inches in every hundred trabochi; and at that spot we propose to take the opening of our canal.
[Footnote: The following are written on the sketches: At the place marked N: navilio da dacquiue (canal of running water); at M: molin del Travaglia (Mill of Travaglia); at R: rochetta ssanta maria (small rock of Santa Maria); at A: Adda; at L: Lagho di Lecho ringorgato alli 3 corni in Adda,—Concha perpetua (lake of Lecco overflowing at Tre Corni, in Adda,— a permanent sluice). Near the second sketch, referring to the sluice near Q: qui la chatena ttalie d'u peso (here the chain is in one piece). At M in the lower sketch: mol del travaglia, nel cavare la concha il tereno ara chotrapero co cassa d'acqua. (Mill of Travaglia, in digging out the sluice the soil will have as a counterpoise a vessel of water).]