Issues of ‘La Nature: Revue des sciences et de leurs applications aux arts et à l’industrie’ (68 vols from 1873 to 1905) which are online at

http://cnum.cnam.fr/

This popular science magazine has many papers on astronomy (written by Camille Flammarion and others) and is illustrated by delightful engravings.

Some of the other scanned items on the website of “Le Conservatoire numérique des Arts & Métiers” (http://cnum.cnam.fr/RUB/fcata.html) may also be of interest to some.