The Pittsburgh Press, Pennsylvania, May 29, 1915

It’s useful because it gives you a glimpse of who is walking behind you. Maybe it’s someone you want to dodge, so when the mirror gives you a hint. You step into a shop or down a side street and escape. Or maybe it’s one of those annoying “Johnnies” coming along - then the mirror is very useful, you can run away from him, or if he looks dangerous you can call an officer.