The threaded posts and metal bar across the top is the frame. The chunk hanging below it with windings is the coil of a piston motor. The shaft connecting that to the cylindrical tin is the piston, and I assume the flat surface of the tin is a diaphragm. The copper tube mounted to the wood is an air vent.
Connect the screw terminals to an amplifier and you've got yourself a homebrew speaker.
That's my guess, anyway.