…to the swift motion given to the middle wheel and then to wheel n. Twenty of drive and one of counter-drive. Every wheel has 100 teeth around its rim, and the pinion 10 spindles.

100, n, 10; 100, 10; 100, e, 10; 100, 10; 100, A, 10; 100, 10; 100, c, 10; 100, 10; 100, b, 10; 100, 10; 100, a, 10; 100, 10; –100, 10; 100, 10; 100, 10; 100, 10; 100, 10; 100, 10; 100, 10; 100, 10; 100, 10; 100, 10; 100, 10; 100, 10; 100, m — 10,000 pounds.

The sun, which warms as much of the world as it sees and which in 24 hours runs so great a course, will — compared with this instrument, that is, with the turning of wheel m brought about by n — seem motionless and cold. Turn first wheel a, then b, then c, then d, then e, and then n; otherwise wheel n would never turn the last wheel m.

Only the poles [pivots] are to stand in running water.

From this instrument four things may result. First, that wheel n, kept in continuous motion by wheel m, will be so slow that no thing on earth so sluggish could be found whose motion would not seem, beside it, like lightning. Second, that wheel m, driven by wheel n, will have so swift a course that every other course, of the sun and of the other planets, will seem most sluggish — as appears in the proof figured below by arithmetic, where, as you see, 1 raises 20 and 20 raises 400 and 400 raises 8000, and so it continues. You shall make the proof of the slowness of wheel n thus: there are 1000 time-units to an hour, and when the first wheel, that is m, turns once in one unit, the second will do likewise in 20, the third will make a full turn in 400, the fourth in 8000; and so you can see, the fourth turning in 8 hours, in how many hours wheel n will have turned. Third, that giving one turn to wheel n, the third [wheel] after it will give 400, and whatever its pole touches that is apt to catch fire will at once catch fire. We have already seen that, the first being cold, the fourth becomes of the nature of common fire, the sixth will be twice as hot, at the 9th it will be at the fourth degree, at the 12th at the eighth, at the 15th at the sixteenth, and so it goes on, so that it would come to such heat that whoever touched the pole of wheel m would die at once. But, to have the said instrument withstand the heat and the fury, the nearer you come to wheel m the finer the poles must be, so that one must take of those diamond points with which cameos are carved, and fix them on the axles of the wheels; and let that which receives the points be also itself a diamond, set thus in a hole (there follows the drawing) as the figure here [shows]; and let the wheels be of fine, well-tempered steel.

n / 1 / 20 / 400 / 8000 / 16000 / 320000 / 6400000 / 12800000 / 256000000 / 5120000000 / 10240000000 / 204800000000 / 4096000000000 / 90920000000000 / 190840000000000 / 3906800000000000 / 79036000000000000 / 158072000000000000 / 3170440000000000000 / 63408800000000000000 / 126907600000000000000 / 2539052000000000000000 / 50790040000000000000000 / 110580080000000000000000 — a hundred thousand million / m: of million of million of million of million of million [of] million. The diameter of the wheels figured above being 1/3 of a braccio, the circumference will be 1 braccio and 1/7. But let us say one braccio, for what is lost in the teeth; so that if you make a point on the said circumference, know that, the said wheel giving a million turns, the point you made will have travelled 333 miles and 1/3, at 3000 braccia to the mile; so make the reckoning. Now think how many miles the said point will travel when wheel n has given one whole turn, which comes to travelling for the said point a hundred thousand million of million of million of million of million of million of million of miles, which it will do in a three-hundredth of an hour; which motion will be given with a weight of 10 thousand pounds drawn by an endless screw. But first begin the motion at the middle wheel, and it will then be easier to turn wheel n, which, giving one turn, m gives a hundred thousand million of million of million of million of million of million of million, as appears in the proof of arithmetic above.

If you want fire quickly, make a similar instrument, but with only six wheels, and have a little dry chestnut wood, and do as you see figured […]