It is about a grid where are placed the shots of photos settled on graves of dead persons.
These images make share some seconds with these dead strangers quite a lot of time ago and a little forgotten. The past to look at these photos is deducted and carried(worn) in the knowledge of the regardeur.
It is a number of seconds which you passed with the photo of these strangers.
The past between the recording and the moment when you see photos is also deducted.

It is a time of the photography..