Upper part of a tower and the 'secret of the compass'
Sketches of a tower with spiral stairs, and details of a drawing compass
The upper half of the sheet gathers a series of sketches of the upper part of a tower, showing spiral stairs and arched openings, with a caption beginning 'all the solid mass of the...'. Below, Leonardo works out details of a drawing compass, headed the secret of the compass and a kind of compasses. The instrument, like its shaft a b, is to be made of four rules together with its matching female piece.
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Upper part of a tower
A group of studies works out the upper part of a tower, with spiral staircases winding inside and arched openings above. A caption begins 'all the solid mass of the...'.
The secret of the compass
At the foot Leonardo details a drawing compass, headed the secret of the compass and a kind of compasses. The part a b is to be made of four rules, and its matching female piece likewise.