"Battery-free Addiator Or Subtractor"
Without battery, without energy… Brilliant mechanism which in its case, fixed on a cast iron base, itself screwed to a board was able to give exact results for decades, in the office where secretaries had to do many operations… I visualize these shorthand typists ticking off the numbers with their stylus before typing the results with their typewriter, on carbon paper in triplicate…. The stylus is replaced by a pencil. Clever system where it was enough to rotate the machine on its desk support to carry out the opposite operations… Addiator and Subtractor rather rare. … around 1920… 
Le Magazine de PROANTIC
TRÉSORS Magazine
Rivista Artiquariato