19th Century Scientific Instrument, With Lamp And Coloured Glass, To Identify

A beautiful old scientific object whose use I have not been able to identify. It consists of a paraffin lamp in the lower part surmounted by a cylindrical chamber and a chimney, the chamber pierced by two vertical rectangular ‘windows’ fitted with translucent glass, one milky white, the other blue.
On the other hand, a movable arm supports a focal lens with two lenses, concave and convex (the concave side is damaged); the cylindrical chamber can be inverted so that either white or blue glass can be displayed behind the lens.
On the side, a square tube set into a larger square fitted with a spring-loaded lever seems designed to release a sliding movement along the longer tube.
If any friendly person can give me some information about this scientific object, including its name, I would be very grateful in advance.
_________________________________________________________________________
I ship all over the world, please ask me for the shipping cost.
_________________________________________________________________________