Why the fancy swirls inside the back cover of a pocket watch?

Dear Cecil: Recently while inspecting the innards of an old pocket watch I noticed the most beautiful dancing swirls on the inside of the back cover. Obviously no one but the watch repairman would ever see these swirls. So what purpose do they serve? L.B.B., Dallas

Cecil replies:

What, you think watch repairmen don’t appreciate the finer things in life? This is the kind of attitude that plays right into the hands of the Sandinistas. The effect you refer to is probably what is known as “engine turning,” a decorative finish commonly applied to metal surfaces with a special lathe. You used to find it quite frequently in fine watches and clocks and even, I am told, on the dashboards of vintage autos. In its simplest form it’s cheaper to apply than the high-gloss finish or other decorative treatment you find on the outside of the watch, but it still beats the appearance of rough metal.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.