"Elevator Trim" on 747-100
 

Just found an old photo of a Polar -100 and on the center pedestal (P8) at the rear left, fwd of the aileron trim switches there is a elevator trim gauge, don't think it was functioning though.
Any Ideas on it's obvious function as there were no trim switches and I don't remember being able to trim the elevators.
Plus unrelated to elevator position indicator.

Sure it's not an old EPR ssytem of some sort? That's where the test system & panel for some of them normally sits.

Nuh it Says " elevator trim" and has +2/-2 units.

*scratches head* ...
Nah, sorry, don't know!
I've flown a few -100's (all ex-JAL) and none of them had anything like that.

Pan Am aircraft had these. They were originally used in conjunction with the INS for fuel savings on long haul flights. On the INS you would select Wind/Hold and it would then show acceleration/deceleration in milli-Gs; you could then use the trim and the throttles to maintain zero elevator displacement and constant speed throughout the the flight. A poor man's PMS I guess.