Sorry, still not available on-line.

Have you checked with the British Library?

BL holdings, 1st series:

Title Le Spectateur militaire. (Recueil de science, d’art et d’histoire militaire.) 1826-51. [SHS: 1st series]
Publisher/year 50 tom. Paris, 1826-50. [SHS: looks like they have complete run - two vols/year]
Physical descr. 8º.
Genre/form Periodical publications.- Paris
Holdings note General Reference Collection M.L.g.15. [Another copy of vol. 42.] Le Spectateur militaire, etc. Paris, 1846. 8º.
Serial holdings Details [SHS: Not viewable on-line!]
Shelfmark P.P.4027. Request
Shelfmark M.L.g.15. Request

I will make an effort to view my Spectateur militaire index to see if I can get the correct pagination for those two items. Or do you already have the correct pagination?