In each of two separate rooms of an apartment a simple sleeping place is installed where you can find an open notebook. The booklet shows illustrations, descriptions and maps to travel the moon. Along with that, pictures of scientists and travellers of the moon are listed.
This compendium is put as a double in each of the places, as if somebody wanted to study it or to proceed with the writings.
Those two places of study are connected by a winding periscope, whose one end focuses the lamp of mattress I, whereas the other end fits into a telescope next to mattress II.
The observation with this arrangement does not describe an interesting outside, but just a replication of the same spot. The flare of the lamp, which can be watched with the periscope is transmitted within a system that simply points at itself.