The analog hydrometer are so inaccurate i toss them in the trash day one.
Get a digital one and calibrate it, they also need calibrating but they don't change calibration like the analog ones do.

I had a nice glass hydrometer i really wanted to use in my main humidor but the damn thing just would not stay calibrated for more than 2 months.
Temperature seams to effect them drastically and down here in SC one week its 40 the next its 75 so mine were changing constantly and utterly useless.