Northern Winds at the Solstice; A Beam Hauled by Angled Cords
The season of the north winds with a wind rose, and a mechanics problem on pulling a beam
The upper notes treat the northern winds, which Leonardo says blow from the winter solstice through the end of January and reach their greatest power in mid-December, accompanied by a compass-rose ('rosa dei venti') diagram labelled a, n, f, m, b and a heading on friction. A lower entry poses a mechanics problem, asking which of several variously angled cords most easily hauls the beam n h, and ranks their effectiveness. A diagram of the beam with radiating cords labelled a, c, d, e, n, b, f illustrates the question.
On this page
The season of the northern winds
The opening note asks why the northern winds begin to blow from the winter solstice and continue through the whole of January. It frames the seasonal timing of these winds as a problem to be explained.
Wind rose: north winds at greatest power
With the compass-rose diagram labelled a - n f m - b, the note states that at the winter solstice, in mid-December, the northern winds are at their greatest power. A short heading 'On friction' (De confregazione) follows.
Which angled cord most easily hauls the beam
The problem asks which cord moves the beam n h most easily and by how much. Cord a does not move it but only lifts; c lifts and moves; d likewise; e does it more easily; and f holds the first rank. A diagram shows the cords a c d e - n b f radiating from the beam.