Springs and counter-levers acting on an iron catch
Why an obtuse angle stalls a spring's return, with geometric sketches above
The main text on folio 49v analyses a spring n r that turns about its pole, with its end n, to push an iron f back again, and explains why it fails: the counter-lever b a that first carried f also swings on its own pole, and once the angle b a f has passed the right angle and become obtuse the line b a opposes the spring's return, so the parts must be set as the last two S-shaped pole figures. Several spring-and-detent mechanisms with flag-shaped arms are drawn across the sheet. At the head of the page are two geometric sketches, a many-sided polygon inscribed in a square and a subdivided rectangle. Further untranscribed text is present between the upper sketches and the mechanisms.
On this page
Spring, counter-lever and the obtuse angle that stalls return
The spring n r wishes to turn about its pole to push the iron f back, but cannot, because the counter-lever b a that first carried f also swings on its own pole. Once the angle b a f, at first right, passes that degree and becomes obtuse, the line b a contradicts the spring; to have effect the parts must stand as the last two S-shaped pole figures.
Polygon inscribed in a square and a divided rectangle
At the head of the sheet a many-sided polygon is inscribed within a square, and beside it a rectangle is divided by internal lines into smaller compartments. No caption accompanies these constructions in the transcription.