The younger of the two Charpentier sons went by the name "Jean," but acts drawn up by two different notaries prove that his full name was "Armand-Jean" — which strongly suggests that he was the godson of a godson of Cardinal Armand-Jean du Plessis de Richelieu. (Richelieu died in 1642, but Armand-Jean Charpentier was not born until 1646 at the earliest.)
In March 1662, sixteen-year-old Jean was apprenticed for three years
to Louis Senault, "maître écrivain" of the rue de "Bussy" (Buci) in the
faubourg Saint-Germain (AN, MC, XXIII, 308, Mar. 15, 1662). At the side
of this master, Jean would learn his late father's craft — specifically,
"l'écriture et gravure en lettres tant fermées que bastarde," in return
for a fee of 200 livres. (Senaillé subsequently engraved the plates for
J-B Alais de Beaulieu's L'Art d'écrire, Paris, 1680). We can
only assume that Jean completed his apprenticeship and became a
maître écrivain juré, for the surviving register book containing
the matricule of the maîtres écrivains of Paris (AN, Y
9335) does not begin until December 1, 1673. This register does,
however, permit me to assert that, some eight years after the end of his
apprenticeship, Armand-Jean had not become one of the ten experts who
directed the corporation.
Indeed, it appears that Armand-Jean
aspired to higher things. By April 1685 (the year when he was chosen to
be one of the guardians for the Édouard children) he had become an
ingénieur du Roy and was living in the "academy" of Antoine de
Vandeuil on the rue de Seine. At that time, the two men signed an
agreement to make a portable flour mill for the royal armies —
specifically, "pour le service du Roy." Any reward from the king would
be shared equally; but if the project failed, Charpentier would
reimburse Vandeuil for his costs and would keep the mill. In this act he
is called "Armand Jean Charpentier" (MC, VI, 582, Apr. 10, 1685) — as he
is in MC, CI, 58, Jan. 16 and Feb. 9, 1688. I attempted to find
Charpentier in the records of the génie at Vincennes (ms. in-fol. 208b,
which contains information for 1683, then jumps to 1689) but in vain.
What did an ingénieur du Roy do? They were specialists in fortifications, they were "able mathematicians" who know the art of fortification. (Anne Blanchard, Les ingénieurs du Roy... (Montpellier, 1979). The record book at Vincennes suggests that these men played an active role in sieges, especially along the northern frontier, and that many of them were badly wounded or even killed. For example, one entry, p. 23, describes as engineer thusly: "Il est joli garçon, déssine bien, entend les toises et a servi au trois sièges." (Incidentally, the apprenticeship of écrivains involved learning mathematics, and therefore how to calculate toises.)
There is no evidence that Armand-Jean ( who continued to use the title ingénieur du Roy until the last document in which he appears) ever married. Indeed, the fact that he continually provides different addresses in the mid-1680s suggests that he lived in rented, perhaps even furnished quarters. For example, notarial acts show him living rue de la Vieille Bouclerie, (Feb. 20, 1685); rue de Seine, at Vandeuil's academy (April 1684); rue de l'Esperon, paroisse Saint-André-des-Arts (Jan.-Feb. 1688); rue Dauphine, same parish (Oct. 7, 1688). Aside from an allusion in Etiennette's will of 1709 to her dead "brothers," no further trace of Armand-Jean Charpentier has been found post-1688. Are we to conclude that he died in the service of the king during the late 1680s and early 1690s?