Studied from its original page
Nomogramme à index en équerre
nomogram with a carpenter's-square index · index en équerre à sommet guidé (square index with guided vertex) · Massau's square for the complete cubic
- Made by
- Junius Massau (square index for the complete cubic, simplified by Maurice d'Ocagne); related square-index charts by R. Soreau and the Siegler profilomètre
- Year
- c.1885
- Field
- Nomograms and computing charts
- Kind
- Computing chart
- Room
- Charts that compute
See the original page — fig. 157, printed p. 386 (archive leaf n410)
Published 1921 (A) and both d'Ocagne (d.1938) and Massau (d.1909) died long before 1955 (B ended 2008 at the latest).
The data it needs
ninput coefficient (vertex path) · quantitativep, qinput coefficients (pinned point (n − q, p)) · quantitativeminput coefficient, quartic only (selects one envelope curve) · quantitativezoutput: one real root per tangent position · quantitative
Built in 6 steps, as its maker described
ch. VI §129, pp. 381–384 (fig. 155, fig. 156); §130, pp. 384–386, fig. 157 p. 386
121 other forms share this skeleton
Source
d'Ocagne 1921, Traité de nomographie, 2e éd. (after Massau)
Attribution less certain: contested, or no single inventor recorded