1503 a 51 T.:  Andata di Leonardo al Campo sotto Pisa.  Spese extraordinarie dieno dare a di XXVI di luglio L. LVI sol.  XII per loro a Giovanni Piffero; e sono per tanti, asegnia avere spexi in vetture di sei chavalli a spese di vitto per andare chon Lionardo da Vinci a livellare Arno in quello di Pisa per levallo del lilo suo. (Published by MILANESI, Archivio Storico Italiano, Serie III, Tom.  XVI.} VASARI asserts:  (Leonardo) fu il primo ancora, che giovanetto discorresse sopra il fiume d’Arno per metterlo in canale da Pisa a Fiorenza (ed.  SANSONI, IV, 20).

The passage above is in some degree illustrated by the map on Pl.  CXII, where the course of the Arno westward from Empoli is shown.]

1007.

The eddy made by the Mensola, when the Arno is low and the Mensola full.

[Footnote:  Mensola is a mountain stream which falls into the Arno about a mile and a half above Florence.

A=Arno, I=Isola, M=Mvgone, P=Pesa, N=Mesola.]

1008.

That the river which is to be turned from one place to another must be coaxed and not treated roughly or with violence; and to do this a sort of floodgate should be made in the river, and then lower down one in front of it and in like manner a third, fourth and fifth, so that the river may discharge itself into the channel given to it, or that by this means it may be diverted from the place it has damaged, as was done in Flanders—­as I was told by Niccolo di Forsore.

How to protect and repair the banks washed by the water, as below the island of Cocomeri.

Ponte Rubaconte (Fig. 1); below [the palaces] Bisticci and Canigiani (Fig. 2).  Above the flood gate of la Giustizia (Fig. 3); a b is a sand bank opposite the end of the island of the Cocomeri in the middle of the Arno (Fig. 4). [Footnote:  The course of the river Arno is also discussed in Nos. 987 and 988.]

Canals in the Milanese (1009-1013).

1009.

The canal of San Cristofano at Milan made May 3rd 1509. [Footnote:  This observation is written above a washed pen and ink drawing which has been published as Tav.  VI in the _,,Saggio."_ The editors of that work explain the drawing as "uno Studio di bocche per estrazione d’acqua."]

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.]