Handwritten calculations of surfaces, masses and costs with profile sketches

In this document

Pages 58-59 contain series of handwritten calculations in pencil, without legend or explanatory statement — a rough work notebook rather than a document intended to be read by a third party.

Surface calculations and conversions

On page 58, there are simple multiplications such as "15x2 = 15 dm²", "15x1.6 = 24" or "15x2.5 = 38.50" p. 58, which seem to explore surfaces in square decimetres for different dimensions. A mention "60 dm² x C.R" p. 58 [uncertain] could refer to a coefficient or an unidentified reference.

Page 59 continues this work with unit conversions: "5 m x 4 = 20" then "x 0.3 = 6 m²" and "8 m² x 1³² = 10.56" p. 59, as well as a final comparison: "13 g. 2 [of dm²] = 1320 gr per square metre" p. 59. This last line is the most explicit in the entire document: it indicates a calculation of surface mass, expressed in grams per square metre from a weighing in grams per square decimetre.

Price or cost series

Long columns of three-line numbers (e.g., "3300 / 2400 / 5400", "14300 / 7200 / 21500", "8200 / 5700 / 13900") occupy a large part of page 59 p. 59, with repeated additions suggesting cost totals or quantities by batch. Their exact nature (materials, parts, rates) is not specified in the text.

Sketches

Page 58 bears two pencil sketches: a symmetrical tapered shape seen in plan, framed by reference lines, and a second drawing in profile evoking a slender aerodynamic or hydrodynamic element p. 58. Page 59 includes a dimensioned sketch of a stepped part, with the dimensions "0.95 / 0.15 / 1.00 / 1.05 / 1.2" p. 59.

Context

At Citroën, Paul Magès conducted numerous studies on part profiles and materials for hydropneumatic suspension, particularly for cylinders and reservoirs. The calculation of a mass per unit of surface suggests a concern for weighing sheet metal or sheet material — a common practice in mechanical pre-series studies of the time, but nothing in this document allows these calculations to be linked to a named project.

Archivist's perspective

These two pages probably come from a rough work notebook where Magès tests surfaces, mentally weighs materials and sketches profiles before transferring them elsewhere — it seems that the link between the tapered sketches and the mass per square metre calculations p. 58-59 is not immediate, which suggests several subjects treated successively on the same medium.

The density and elliptical nature of the notes make precise dating impossible; no clue (date, header) appears in the transcriptions. The comparison with other items in the same collection, such as the dimensioned sketch of the hydropneumatic oil reservoir, could clarify the function of the stepped part drawn on p. 59, without documentary certainty.