The Blow of a Staff Struck at Two Points
Impact and weight of a rod, with a perspective mechanism sketch and jotted numbers
The lower text argues that the blow of a staff c d striking at its end a carries the staff's whole weight, while a blow at b carries only half; yet because the descent d b is double the descent n a, the blow is doubled, so the two blows come out equal. Around the writing are geometric diagrams: a circle with an inscribed triangle and a right-angled wedge set beneath a semicircular arc, illustrating the descents compared in the text. At the top, in chalk and ink, an apparatus is sketched in perspective, and a column of numerals runs along the sheet with the page turned upside down. A separate note reads simply 5 1/2.
On this page
Blows at the end and the middle of a falling staff are equal
The staff c d striking at a delivers the whole weight of the staff; striking at b it delivers half that weight. But because the descent d b is double the descent n a, the blow at b is doubled, so the two blows are concluded to be equal to one another. Points d, n, c, b and a label the staff and its two fall-paths.
Circle with inscribed triangle and a wedge under a semicircular arc
Below the top sketch a circle carries an inscribed triangle with marked centre points. Beneath it a long right-angled wedge sits under a semicircular arc, the construction against which the doubled and halved descents of the staff are measured.
Apparatus sketched in perspective at the top
Across the top of the sheet, in red chalk and pen, a mechanism or frame is drawn in perspective with long converging rails. It is only lightly indicated and is not covered by the transcribed text, so its exact function is not given.
Column of numerals with the sheet inverted
With the page turned upside down a run of single digits and short number-rows is written out, apparently loose calculation. A separate jotting at the foot of the sheet gives 5 1/2.