Remnants of an old emergency lighting system (50v GLS lamps)

In a building that will be refurbished. For this reason, I managed to acquire 4 of these 50v lamps. These lamps I presume would have been lit using a backup power source to illuminate the doors on each floor of the stairwell in the event of a power outage. I had never seen such a system in place before (albeit it probably hadn't worked in decades, some floors were missing their lamps - also the lamps are most certainly original to the building).