Looks like hill & dale (vertical cut) recording. I would say that the left side shows a recorded groove and the right side shows the lead screw used to move the cylinder relative to the cutter head. (Could be that the cutter head is moved by the lead screw but moving a cutter attached to a vast recording horn is far more cumbersome than moving the cylinder. I believe in the days of acoustic recording it was more common to move the recording medium rather than the cutter for this very reason)
An Edison tinfoil cylinder machine.
This may be a lath in the process for spinning a disc of alluminium to produce a trumpet shaped horn for a clockwork gramaphone
Perhaps this is a cylinder master recording in the process of recording onto a foil
The word “lath” in my first reply should have been Lathe
This is a closeup view of the 1888 Gramaphone cylinder section
Looks like hill & dale (vertical cut) recording. I would say that the left side shows a recorded groove and the right side shows the lead screw used to move the cylinder relative to the cutter head. (Could be that the cutter head is moved by the lead screw but moving a cutter attached to a vast recording horn is far more cumbersome than moving the cylinder. I believe in the days of acoustic recording it was more common to move the recording medium rather than the cutter for this very reason)