The only Sheridan I am familiar with is an air pistol that had a pump olever under the barrel. It was a pretty good air pistol, for a plinker, sold for about $80 in the 1980's. It was a single shot and either a .22 or a 5mm pellet.
I believe some people collect them, and if yours is from the 1940's and in good working condition, it may be worth a few dollars to an interested party.
mark