... it is tempered by putting sand or gravel in the vessels. ... [a material] that does not draw back against weight and is not tempered except in a month.

b a. The vessel a, in filling in one hour, opens the little tap b, which in another hour does the same; and so they continue up to 24 hours, one vessel per hour. And they are small, and they open the large vessels when they open at the second vessel.

e d c b a - i h g f. With the aid of the sixth of the fourth, the vessel a b pours its water into vessel f and raises the float found in it, with a sudden release of that sixth. Which, released, at once comes afloat and opens the tap b with its little valve, and at the same time opens behind it, with the same quickness, the vessel that sounds the hours. Here three vessels are used, of which the first is a, and this pours out exactly in one hour, as do all those set in the same line. The lower vessels fill in the same hour in which the one above pours into them, and in filling, the lower vessel raises and releases the float of the second vessel b in the manner said of the sixth. So vessel b empties and vessel g fills in a second hour, and the vessel behind sounds its hours. On opening the tap at b, the vessel of the hours opens; and when vessel g empties by the manner of the fourth with a siphon, the vessels close again; and when 24 hours have sounded, in one following hour all the vessels that release the hours and those that sound the hours refill. But the lower vessels need not refill except hour by hour, as is said.

(⁴3 244-816. All the water leaving each vessel that sounds the hours comes by one same channel to one same wheel of eight spokes, which wheel at once fills one of those little boxes; they descend held back by an escapement so that they can wait to be full and their descent does not run with force.

o g

All the cisterns that sound the hours are to be filled between the 24th and the first hour; and the first does not sound but takes barely an hour to pour out its water and then releases the cistern of the first hour.

seventh

b -a. When the bucket a, in contact with the spout b, fills and has its due weight, it separates from that spout and descends with fury the height of half a braccio. In separating from the mouth of the spout, that mouth closes with the aid of the seventh; and this bucket descends and raises the hammer by the order of the eighth and strikes the bell; and at once the bucket, having reached the ground, empties by the order of the third, and so becomes light and returns upward by means of the hammer that descends; and having reached the spout, it unlocks it by the order of the second, and so refills anew and descends anew by the same rule stated, continuing until its hours are sounded.

1/3 —25 —25

a -b -c -d. A bottom that opens on touching the ground d; and all the water pours out.

15 15 16 16 17 17 18 18 / 75 256 289 324 / 15 96 / 225 16 / (2²⁵ 256