1010.

OF THE Ca.n.a.l OF MARTESANA.

By making the ca.n.a.l 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 ca.n.a.l navigable. The ca.n.a.l had been made in 1460 by Bertonino da Novara. Il Moro issued his degree in 1493, but Leonardo's notes about this ca.n.a.l were, with the exception of one (No. 1343), written about sixteen years later.]

1011.

No ca.n.a.l which is fed by a river can be permanent if the river whence it originates is not wholly closed up, like the ca.n.a.l of Martesana which is fed by the Ticino.

1012.

>From the beginning of the ca.n.a.l to the mill.

>From the beginning of the ca.n.a.l 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 ca.n.a.l 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 ca.n.a.l.

[Footnote: The following are written on the sketches: At the place marked N: navilio da dacquiue (ca.n.a.l 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 ca.s.sa d'acqua. (Mill of Travaglia, in digging out the sluice the soil will have as a counterpoise a vessel of water).]

1013.

If it be not reported there that this is to be a public ca.n.a.l, it will be necessary to pay for the land; [Footnote 3: il re. Louis XII or Francis I of France. It is hardly possible to doubt that the ca.n.a.ls here spoken of were intended to be in the Milanese. Compare with this pa.s.sage the rough copy of a letter by Leonardo, to the "Presidente dell' Ufficio regolatore dell' acqua" on No. 1350. See also the note to No. 745, 1. 12.] and the king will pay it by remitting the taxes for a year.

Estimates and preparatory studies for ca.n.a.ls (1014. 1015).

1014.

Ca.n.a.l.

The ca.n.a.l which may be 16 braccia wide at the bottom and 20 at the top, we may say is on the average 18 braccia wide, and if it is 4 braccia deep, at 4 dinari the square braccia; it will only cost 900 ducats, to excavate by the mile, if the square braccio is calculated in ordinary braccia; but if the braccia are those used in measuring land, of which every 4 are equal to 4 1/2 and if by the mile we understand three thousand ordinary braccia; turned into land braccia, these 3000 braccia will lack 1/4; there remain 2250 braccia, which at 4 dinari the braccio will amount to 675 ducats a mile. At 3 dinari the square braccio, the mile will amount to 506 1/4 ducats so that the excavation of 30 miles of the ca.n.a.l will amount to 15187 1/2 ducats.

1015.

To make the great ca.n.a.l, first make the smaller one and conduct into it the waters which by a wheel will help to fill the great one.

Notes on buildings in Milan (1016-1019)

1016.

Indicate the centre of Milan.

m.o.f.orte-porta resa-porta nova-strada nova-navilio-porta c.u.mana-barco-porta giovia-porta vercellina-porta sco Anbrogio-porta Tesinese-torre dell' Imperatore- porta Lodovica-acqua.

[Footnote: See Pl. CIX. The original sketch is here reduced to about half its size. The gates of the town are here named, beginning at the right hand and following the curved line. In the bird's eye view of Milan below, the cathedral is plainly recognisable in the middle; to the right is the tower of San Gottardo. The square, above the number 9147, is the Lazzaretto, which was begun in 1488. On the left the group of buildings of the 'Castello' will be noticed. On the sketched Plan of Florence (see No. 1004 note) Leonardo has written on the margin the following names of gates of Milan: Vercellina -Ticinese-Ludovica-Romana-Orientale- Nova-Beatrice-c.u.mana-Compare too No. 1448, 11. 5, 12.]

1017.

The moat of Milan.

Ca.n.a.l 2 braccia wide.

The castle with the moats full.

The filling of the moats of the Castle of Milan.

1018.

THE BATH.

To heat the water for the stove of the d.u.c.h.ess take four parts of cold water to three parts of hot water.

[Footnote: d.u.c.h.essa di Milano, Beatrice d'Este, wife of Ludovico il Moro to whom she was married, in 1491. She died in June 1497.]

1019.

In the Cathedral at the pulley of the nail of the cross.

Item.

To place the ma.s.s v r in the...

[Footnote: On this pa.s.sage AMORETTI remarks (Memorie Storiche chap. IX): Nell'anno stesso lo veggiamo formare un congegno di carucole e di corde, con cui trasportare in piu venerabile e piu sicuro luogo, cioe nell'ultima arcata della nave di mezzo della metropolitana, la sacra reliquia del Santo Chiodo, che ivi ancor si venera. Al fol. 15 del codice segnato Q. R. in 16, egli ci ha lasciata di tal congegno una doppia figura, cioe una di quattro carucole, e una di tre colle rispettive corde, soggiugnandovi: in Domo alla carucola del Chiodo della Croce.

AMORETTI'S views as to the mark on the MS, and the date when it was written are, it may be observed, wholly unfounded. The MS. L, in which it occurs, is of the year 1502, and it is very unlikely that Leonardo was in Milan at that time; this however would not prevent the remark, which is somewhat obscure, from applying to the Cathedral at Milan.]

1020.

OF THE FORCE OF THE VACUUM FORMED IN A MOMENT.

I saw, at Milan, a thunderbolt fall on the tower della Credenza on its Northern side, and it descended with a slow motion down that side, and then at once parted from that tower and carried with it and tore away from that wall a s.p.a.ce of 3 braccia wide and two deep; and this wall was 4 braccia thick and was built of thin and small old bricks; and this was dragged out by the vacuum which the flame of the thunderbolt had caused, &c.

[Footnote: With reference to buildings at Milan see also Nos. 751 and 756, and Pl. XCV, No. 2 (explained on p. 52), Pl. C (explained on pages 60-62). See also pages 25, 39 and 40.]

Remarks on natural phenomena in and near Milan (1021. 1022).

1021.

I have already been to see a great variety (of atmospheric effects). And lately over Milan towards Lago Maggiore I saw a cloud in the form of an immense mountain full of rifts of glowing light, because the rays of the sun, which was already close to the horizon and red, tinged the cloud with its own hue. And this cloud attracted to it all the little clouds that were near while the large one did not move from its place; thus it retained on its summit the reflection of the sunlight till an hour and a half after sunset, so immensely large was it; and about two hours after sunset such a violent wind arose, that it was really tremendous and unheard of.

[Footnote: di arie is wanting in the original but may safely be inserted in the context, as the formation of clouds is under discussion before this text.]

1022.

On the 10th day of December at 9 o'clock a. m. fire was set to the place.

On the l8th day of December 1511 at 9 o'clock a. m. this second fire was kindled by the Swiss at Milan at the place called DCXC. [Footnote: With these two texts, (l. 1-2 and l. 3-5 are in the original side by side) there are sketches of smoke wreaths in red chalk.]

Note on Pavia.

1023.