The instructions, translated, read:

Maragioscope
Manière de se servir de l'appareil
Open the apparatus by pulling up the corners, which are folded inside. Put the lens in the round opening. Fix with gum or bees wax a transparent square paper on the clear glass.
Open and fix the hood in the two copper hooks, and direct the apparatus towards the item you want to draw. If the object you are drawing is rather far away (a landscape, for example) you have to put the glass side next to the opening. If on the contrary the object is rather near (like a portrait or a print) you will have to put the glass outside, and lengthen or shorten the tube so that the image is clear on the paper.
You have to have a good light on the item you are drawing, and place the Miragioscope as much as in the shadow as you can.