On the power of the voice.

a f n b – columnar – e – c d

a b c d – e f g h. As much as the voice a b receives into itself the voice f n, so much more powerful is the ear c d, receiving more voice from a b than from f n. And because in effect a b is almost infinitely greater than f n, the voice, striking the ear c d, becomes infinitely greater than if it were struck by the said f n.

p a o – not very useful – x S r v b p z h d – n o m – y g c. Here follows what is missing below, opposite. To find the true curvature of a circle that has for its semidiameters the two sides of a triangle, where this circle is to be centred on the angle of those two sides, and where those sides do not reach that centre or angle — as would be the two lines r n and v m — then you shall make a circle centred on the end of one of the two lines, that is of the line r n: the centre is placed at the end n, and you will do the like at the end m of the line v m. This done, upon m take the equal space that the parts of the circle b c and b d have, and draw the diameter c d of the circle. Do the like on the opposite circle upon the centre n. Having done this, draw the line n m between the two centres n and m. And do the like opposite, making the three angles h g S, which are the angles of a hexagon. Then make the two angles n m of the middle hexagon, and lastly make the angle m of a smaller hexagon, that is the angle x y z. Then open the compass and set the fixed foot upon the angle a, where the two given lines n r and m v meet, and set the moving foot upon the point m, and you will make the asked-for circle p n m o.

Let the two given lines be of equal obliquity. This is for making a part of a circle where there is neither periphery nor centre — a circle that would be 25 or 30 miles in diameter.

You shall draw the circumferential line with the great lance of uniform thickness.