[NJARC] Mystery Clarostat in Mystery Radio

[StephenTetorka at cs.com]

Hi all:

Picked up this 1931 tombstone radio called "President"...most likely made in 
NYC.

Trying to figure out who made it....but now trying to get it working....

There's a Clarostat control that looks like a potentiometer on the front 
chassis.

I got not resistance reading whatsoever...and took it apart to see if I might 
fix it.

Curious thing I've ever seen:

There a flat black wax object - 1 in long 1/2 in wide 1/8 in thick uder the 
back rear hard cardboard cover..connected to one lug with very fine wire...the 
other end goes inside to the front section where there is NO wire to be 
seen...just this armature which revolves onto a flat soft surface..like very, very 
fine felt...at the end of the rotating armature is a itsy-bitsy gear which 
travels around the inside outer-perimeter...

I probed the felt-like material...no ohms anyplace...

Even thought it might be some kind of vintage variable capacitor as I got no 
ohms...???

One lug on this control is connected to ground...the other end to the grid of 
a 47 amp feeding the speaker...one of two 47's that look like they are in 
parallel.

Anyone have any ideas?

Tnx,
Steve Tetorka