Aesthetics
I personally think that the 10:10 position (sometimes 10:12 or 10:08) was adopted for pictures of clocks and watches because it is symmetric and looks better. Today the symmetric positions are both aesthetic and customary. Other symmetric hand positions are also used, but not as frequently. Examples include 8:20, 8:18, and 2:50. Reviewing some Seth Thomas clock catalog illustrations, I see a gradually increasing symmetry of the hands as the catalogs progress from 1878 to 1940.
"Smile" Theory
It has been suggested that the 10:10 position is used because it resembles a smile.
"I too have heard the 'smile' theory, which makes some sense from the emotional marketing perspective. Equally likely is the fact that most manufacturer's trademarks are just above the center pipe, and having the hands at 10:10 causes your eye to naturally follow to the trough, thus bringing your view right to the trademark." - Tom Frank
Time of Abraham Lincoln's Death
U.S. President Abraham Lincoln died at 7:22 a.m. on April 15, 1865, although he was shot at 10:15 p.m. on April 14, 1865. Although this has been suggested, I doubt that the position of the hands commemorates the time of Lincoln's assassination or death.
Source & More
why the time is 10:10:35secs in new clocks
Linear Mode
