Overview Level of Folio 80 r


Size Height 280 mm, width 187 mm.
Watermark Two watermarks. Unicorn with 4 legs, little circle on top of the forehead. Crown with encircled cross. Drake's identification: Watermark type 13. Drake's description: Rhinoceros 75mm (smaller on letter cited?). Date of earliest letter with this watermark is August 1607.
Comments Written by Galileo; contains text, drawing, calculation. Relation to the Discorsi: statement and elaboration of 3/08-th-05.
References Caverni 1972 555-556; Damerow et al. 1992 216-218, 353; Naylor 1974a 336 footnote; Renn 1990 101
Folio 80 r (final text)
1A In [tri]ang[ul]o rectangulo bcd fiat angulo d aequalis angulus cbe, et iungatur eb: erunt ergo 2 [tri]ang[ul]a dcb, ebc similia. Dividatur tota dc bifariam in h et parallela hi sit ipsi cb. Dividatur pariter ec bifariam in f, et ducatur fg parallela bc, et fiat ut dh ad hi ita hi ad hl, et iungatur li: erit [tri]ang[ul]um lih simile [tri]ang[ul]o dhi, et ob id simile quoque ipsi efg; sed hi est aequalis gf (utriusque enim dupla est bc), ergo reliqua latera hl, fe aequalia erunt; quare ter[t]ia proportionalis ipsarum lh, hi, nempe hd, erit aequalis [tertia]e proportionali ipsarum ef et fg. Sed [terti]a proportionalis ipsarum lh, hi est hd, dimidia nempe totius dc: ergo [terti]a proportionalis ipsarum ef, fg aequabitur dimidiae cd, nempe ipsi ch.
1B Sed ch est aequalis fl, cum cf sit aequalis hl, et fh communis: ergo [terti]a proportionalis ipsarum ef, fg erit fl, terminata in puncto l, ubi terminatur [terti]a proportionalis ipsarum dh, hi. Ex hoc demonstrabitur proiectorum secundum elevationes a semirecta per angulos [a]equales factorum amplitudines parabolarum esse aequales.
C01 22_38 1/2


Overview Level of Folio 80 r