Old men

The academie started in 1666 with several members who were allready well over 60 year: All these could be any one of the four elderly men (3, 9, 12, 15).
As 3, 4 (Cl Perrault) and 6 (Mariotte) seem to form a group of physicians of sorts, 3 could be De La Chambre or Duclos.
The numbers 9 and 12 seem to be part of a cluster of Geometers headed by Huygens which would make them Frenicle de Bessy (9) and Roberval (12).
Number 15 is another old man, who has some features of De La Chambre.
The one person missing is Carcavy, but as he is also the Royal Librarian, he might be situated elsewhere in the picture.