Calculations on petrol injection and address of a convalescent home in Mégève

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Page 53: calculations on petrol injection

The page opens with the heading "Injection essence" (Petrol injection) accompanied by two pairs of dimensions, d=60 / D=88cm²30 and d=104 / δ=85cm p. 53. Several blocks of handwritten pencil calculations follow: multiplications and divisions concerning areas ("cm²"), volumes ("cm³"), flow rates ("200 l. per minute", "200 litres of air per minute at atmospheric pressure") and ratios linked to engine revolutions ("0l.04 per 1/2 turn", "0l.08 per engine revolution") p. 53.

A second group of calculations, located lower down, follows a similar logic: diameters d=55, d1=8,5, areas S=23.75, δ1=56.75, and a series "S 90 = 63,6 / S1 60 = 28,3 / δ-δ1 = 35,3 cm²" leading to a "Volume generated per engine revolution = 45cm³ x 4 = 90 cm³" p. 53. The mention "V. Purge 1/2 tour moteur" (V. Purge 1/2 engine revolution) also appears p. 53.

A small perspective sketch of a cube or parallelepiped is drawn in pencil in the centre of the page p. 53. At the top of the page, a note explicitly refers: "Voir au dos pour adresse de la maison de repos" (See overleaf for address of the convalescent home) p. 53.

Page 54: address note and supplementary calculations

The top of the page, in blue ink, bears the text: « Le repos à la Montagne » — Chalet du Christinet à Mégève (Hte Savoie) ("Rest in the Mountains" — Christinet Chalet in Mégève (Upper Savoy)), "reserved for young people aged 15 to 25", with a secretariat "à Paris - 14, rue Jean Dolfus prolongée (18e)" (in Paris - 14, rue Jean Dolfus prolongée (18th district)) p. 54.

Below, in pencil, numerical calculations continue (ratios, proportions of the type "0,7 = 84 / 1 x", conversions of grams and centimetres) without an explicit technical heading p. 54.

Context

Throughout his career at Citroën, Paul Magès conducted numerous studies on engine fuel supply and injection, in parallel with his best-known work on hydropneumatic suspension. The subject of "petrol injection" mentioned here is part of this type of automotive engineering research, common in design offices in the 1930s-1950s.

The mention of a convalescent home for young people in Mégève, in Upper Savoy, relates to a private use of the paper — a frequent practice among engineers of the time who reused the back of their calculation drafts to note personal information.

Archivist's view

This double page clearly illustrates the material texture of Magès's working archives: dense technical calculations, difficult to interpret in isolation, coexist with a trace of daily life noted in haste on the back of the sheet p. 53-54.

The explicit reference "Voir au dos pour adresse de la maison de repos" p. 53 shows that the sheet was indeed intentionally reused, with no thematic link between the two sides.

The calculations of areas, diameters and volumes per engine revolution recall, by their structure, other sizing studies kept in the same collection, such as the handwritten proposal for a constant oil level system or the "1933" folder listing studies on injection and the carburettor, which confirms that this theme of petrol injection was part of Magès's work programme as early as the 1930s. It therefore seems that this page belongs to this same vein of research, without it being possible here to specify the date or the exact context of the calculation further.