I took the top photo on my last hike (not published on HAZ yet). Lower photo is a vintage dry cell battery on Ebay.
Lower photo = The center, threaded terminal is positive and the outer edge terminal is negative. The negative 'post' just goes down to the other end of the battery. (ie just like our batteries today, one end is pos (+) & the other is neg (-), except on the vintage batteries, they wanted both + and - next to each other.
My top photo has the 'remains' of the negative terminal/threaded post. (center piece with threaded top). The far right piece is probably remnants of the positive post.
Anyway, I'm convinced (like nonot's comment), these things are dry cell batteries.
My speculation is:
Surveyors do their surveying and set the disk.
Then the surveyors leave the mountain, leaving one crew member behind to power a light installed on the 'Height of Light' pole with a dry cell battery.
Once the departed surveyors reach the azimuth mark or another benchmark (and nighttime arrives), the crew member left on the mountain powers the light with the dry cell battery (on a pre-arranged signal), and measurements are taken by the far away surveyors.
After the measurements are taken, the actual light (and its wires) are disconnected from the dry cell battery and taken off the mountain with that remaining crew member. The now used-up dry cell battery (or batteries) are discarded on the mountain.
Hey - Are we having fun or what???