Unknown compass

I have had this compass for a number of years and have never seen another like it, I hope someone can identify it and what it was used for. It is brass painted black, its unusual as the middle of the compass has an accordion design and you can actually move it a little. It has degrees instead of the usual North/South. No markings on the compass, it looks like it may fit into some type of holder. There is a filler hole, the liquid is petroleum based, or mineral oil.

Any help is appreciated.

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Is it see through? If so, it could be a magnifying chart compass. Sometimes used at reading nautical charts. It would fit into a holder that legs to get magnification. Some rotated in the holders to adjust the amount of magnification. Just a guess.

Yes, its see through, but the compass could be considered small as its only 1.5" across. I am impressed with the dial and how intricate it is.