The Conduit and Siphon of the Garden of Blois
Diagram of the aqueduct built in France by Fra Giocondo, with siphon a b c d e f g
A schematic red-chalk diagram of a water conduit and siphon, lettered a b c d e f g, that carried water to the garden of Blois in France. The transcription, attributed by Leonardo to the conduit built by Fra Giocondo, explains each segment: a b is the conduit itself, b c the shortfall in its height, c d the height of the garden of Blois, e f the fall of the siphon b c e f, and f g the point where the siphon discharges into the river. The drawing lays out these lettered lines as a rectangular plan and profile of the waterworks.
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Siphon carrying water to the garden of Blois
The lettered scheme traces the water's path: a b is the conduit made in France by Fra Giocondo, b c the deficiency of its height, c d the height of the garden of Blois. The segment e f is the fall of the siphon b c e f, and f g is where the siphon pours into the river.
The conduit built by Fra Giocondo in France
The note records a real French waterwork, the conduit of Blois built by Fra Giocondo, analysing why its height falls short (b c) relative to the garden it must supply (c d). The drawing sets out the built work as a measured layout.