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 space 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.
The chimneys of the castle of Pavia have 6 rows of openings and from each to the other is one braccio.
[Footnote: Other notes relating to Pavia occur on p. 43 and p. 53
(Pl. XCVIII, No. 3). Compare No. 1448, 26.]
Notes on the Sforzesca near Vigevano (1024-1028).
1024.
On the 2nd day of February 1494. At Sforzesca I drew twenty five steps, 2/3 braccia to each, and 8 braccia wide.
[Footnote: See Pl. CX, No. 2. The rest of the notes on this page refer to the motion of water. On the lower sketch we read: 4 br. (four braccia) and giara (for ghiaja, sand, gravel).]
1025.
The vineyards of Vigevano on the 20th day of March 1494.
[Footnote: On one side there is an effaced sketch in red chalk.]
1026.
To lock up a butteris at Vigevano.
1027.
Again if the lowest part of the bank which lies across the current of the waters is made in deep and wide steps, after the manner of stairs, the waters which, in their course usually fall perpendicularly from the top of such a place to the bottom, and wear away the foundations of this bank can no longer descend with a blow of too great a force; and I find the example of this in the stairs down which the water falls in the fields at Sforzesca at Vigevano over which the running water falls for a height of 50 braccia.
1028.
Stair of Vigevano below La Sforzesca, 130 steps, 1/4 braccio high and 1/2 braccio wide, down which the water falls, so as not to wear away anything at the end of its fall; by these steps so much soil has come down that it has dried up a pool; that is to say it has filled it up and a pool of great depth has been turned into meadows.
Notes on the North Italian lake. (1029-1033)
1029.
In many places there are streams of water which swell for six hours and ebb for six hours; and I, for my part, have seen one above the lake of Como called Fonte Pliniana, which increases and ebbs, as I have said, in such a way as to turn the stones of two mills; and when it fails it falls so low that it is like looking at water in a deep pit.
[Footnote: The fountain is known by this name to this day: it is near Torno, on the Eastern shore of Como. The waters still rise and fall with the flow and ebb of the tide as Pliny described it (Epist. IV, 30; Hist. Nat. II, 206).]
1030.