need to ID an old air rifle

its made by "crosman arms co.", pat. oct. 28 1924. i dont know how to upload a picture so i cant show you it, does anybody know what this might be? the crosman arms co is printed on the right side of the receiver, which appears to be finished with some black paint. just looking at it i would estimate the barrel to be 20 inches or less, the barrel sits on top of a air tube with some sort of plunger that i assume, provides the propelling force to the pellet. i do not think this gun works as i beleive the air tube leaks. does anyone know what this thing is and maybe how much it would be worth?