how to properly mount a swivel arm lamp?

I picked up these swivel arm lamps on craigslist, I do not know how to mount them properly, it seems like they are missing pieces, but i am not sure. if someone has one of these or knows how to install them i would appreciate it thanks

Picture of how to properly mount a swivel arm lamp?
iceng6 years ago
Bedside Mounting and something Extra to avoid wall scratches.
frollard6 years ago
There should be an L shaped round rod that slides into the horizontal cylindrical hole. The rod has a threaded end that then faces down and hangs over the edge of the desk. A threaded thumb-turn-nut then holds a bracket that clamps to the bottom of the desk. (think of the shape of an adjustable C-clamp).

They also seem to have vertical holes that you could screw them directly to the desk. The lamp arm has a spindle that is inserted into a vertical hole on the clamp. shows the clamp.
embochner (author)  frollard6 years ago
thanks for answering- i do not have an L shaped round rod, threaded end, threaded thumb-turn-nut. any ideas for what i can use to keep the lamp inside the mount?
The mount stays vertical, and the lamp just rests in it - you need a way to clamp the mount to the desk.