Any idea for year period?

Hi dear friends, I recently found this old lady. Optimus 200, what is your manufacturing year guess?
Best wishes.

 

Very late 1930s to first half of 1940s. This is the last variation with the text on the tank like that.

I am guessing that the inner top is from a Petromax, or at least the mixing tube is. Optimus never had an adjustment screw on the mixing tube.

 

Thanks for your valuable determining