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Library/Paris Manuscript G/151

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Paris Manuscript G — 151

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Bibliothèque de l'Institut de France, Paris

Stucco.

Fa stucco sopra il gobb[o] dell'aengi1 di gesso, il quale sia composto di erenev et oirucrem, e impasta bene sopra esso gobbo con equal grossezza di costa di coltello fatta colla sagoma, e questa copri con coperchio di campana da stillare, e riarai il tuo umido con che impastasti. El rimanente asciuga bene e poi infoca e batti ovver brunisci con buon brunitoio, e fa grosso in verso la costa.

Stucco.

Polverizza il ortev e con ecarob e acqua impasta e fa stucco. E poi scalda in modo si secchi, e poi vernicia con foco2, in modo ben lustri.

De refressione.

Diagramma, con:

a b n o q - c e - d f - m p r f

Quando l'aste del polo fussi corta, ella sarebbe sì potente, che la sagoma si potrebbe adoperare come ella è situata, e appoggerebbesi e aggraverebbesi sopra c d, che sarebbe al nostro proposito per causa del consumare la cosa confregata, ecc.

a b c d incidenzia ha la sua refressione in c d f. Ma questa debbe essere disegnata in sito piano, e poi fatto in opera per diretto, cioè che c d sagoma si trovi sotto per diritto al e f polo, o voi dire centro del circunvolubile, perché se tu la mettessi in opera come ella è figurata, il peso del suo sporto la piegherebbe, ovver guasterebbe il predetto centro.

Stucco. Make stucco over the boss/form of plaster, which is composed of copper and mercury, and knead it well over that boss to an even thickness of a knife's back, shaped with the profile-template; and cover this with the lid of a distilling bell, and you will draw off the moisture with which you kneaded it. Dry the rest well, then heat it and beat it, or else burnish it with a good burnisher, and make it thick toward the edge. Stucco. Pulverize the glass and, with borax and water, knead it and make stucco. Then heat it so that it dries, and then varnish it with fire so that it shines well. On reflection.

Diagram, with:

a b n o q - c e - d f - m p r f. When the shaft of the pole were short, it would be so powerful that the template could be used as it is situated, and it would lean and bear down upon c d, which would suit our purpose because of the wearing away of the rubbed thing, etc. The incidence a b c d has its reflection in c d f. But this must be drawn on a flat plane and then carried out straight in practice, that is, so that the template c d lies directly beneath the pole e f, or say the center of the revolvable body; because if you put it into practice as it is drawn, the weight of its projection would bend it, or else would spoil the said center.

Stucco recipes and a revolvable shaping template

Copper-mercury and glass-borax stuccos; a template on a pole and the geometry of reflection

Machines & Devices Optics & Light

Two facing recipes for stucco open the page: one of copper and mercury spread over a plaster form to the thickness of a knife's back and burnished, the other of powdered glass kneaded with borax and varnished with fire until it shines. The heading 'On reflection' then introduces the device drawn below, in which a profile-template (sagoma) mounted on a pole bears down on c d to shape a revolving piece. Leonardo works out the geometry of incidence and reflection (a b c d / c d f) and warns that the template must sit directly beneath the pole's center, or the weight of its projection will bend the shaft and spoil that center.

On this page

Revolvable template mounted beneath a pole

A profile-template (sagoma) is carried on a shaft so that it bears down on c d; Leonardo notes that a short pole-shaft would be strong enough to use the template as situated. He warns the template c d must sit directly beneath the pole e f, the center of the revolvable body, or the weight of its projection would bend the shaft and spoil the center.

Line of incidence a b c d and its reflection c d f

The incidence a b c d is said to have its reflection in c d f. Leonardo instructs that this must first be drawn on a flat plane and then carried out straight in practice, keeping the template aligned with the axis.

Reader's Edition — described with AI from the e-Leo transcription.