University of Chicago Centennial Cataloguesback
Michelson's "she-devil" ruling machine
Michelson's "she-devil" ruling machine.

Michelson labored for thirty years to perfect his temperamental ruling machine, which he said required "humoring, coaxing, cajoling - and even some threatening!" The machine cut thousands of parallel grooves on small plates of metal. These diffraction gratings were crucial for analyzing light.