Firing props to collapse a wall; cube-root scale
Timed powder charges undermine a wall; the statics of a prop (m o n a) and a construction of cube roots.
This crowded sheet joins a siege demolition scheme to studies of statics and geometry. A marginal note describes charging wooden props with powder and firing them all at once by pulling a single cord, so the props burst and the wall they carry collapses; a lettered diagram (m o n a) analyzes when such a prop stays stable and when it gives way. Turning the sheet, a large right-triangle construction lays out the cube roots of 1 through 8 along lettered lines, and a column of figures is jotted at the lower right. A faint chalk figure and further untranscribed under-drawing also appear.
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Collapsing a wall by firing its props
Wooden props are packed with powder at several heights and linked so that pulling one cord fires them all at the same instant. The props burst in many places and the wall they were supporting immediately falls—a mining or demolition device against fortifications.
Statics of a wall on a prop (m o n a)
In the lettered diagram, while the wall m stands over o both wall and prop n o are stable; when m pushes toward n the prop still holds, because line m n is founded on the ground at n. Only when m is thrust beyond a does the prop find no support, give way, and let the wall fall.
Construction of the cube roots 1 to 8
With a e and p c set as equal spaces and p c taken as the cube root of one, the diminishing divisions p e, p n, p m ... a give the roots of 1, 2, 3 ... up to a, where p a is the cube root of 8. The divisions are first stepped off along a f of line a b, then carried by lines drawn from c through f.
Column of figures
At the lower right a short column of numerals is jotted—8, 7, 6, then 1 8 . 8 4, and 4—apparently working figures accompanying the constructions above.