About the Design:

The Mercury dime is a ten-cent coin struck by the United States Mint from 1916 to 1945. Designed by Adolph Weinman and more correctly referred to as the Winged Liberty Head dime, it gained its common name as the obverse depiction of a young Liberty, identifiable by her winged Phrygian cap, was confused with the Roman god Mercury. 

Obverse
An allegory of Liberty wearing a winged Phrygian cap (freedom of thought) is surrounded with the word "LIBERTY" and accompanied with the motto: "IN GOD WE TRUST"

Lettering: LIBERTY IN GOD WE TRUST 1919 AAW

Reverse
A fasces mixed with an olive branch shows both that United States are prepared for the war and their desire for peace. It is accompanied with the motto "E • PLURIBUS UNUM" and surrounded with the facial value and the lettering "UNITED • STATES • OF • AMERICA"

Lettering: 
E • PLURIBUS UNUM
UNITED • STATES • OF • AMERICA
* ONE DIME * 
D

Weight            2.5 g
Diameter    17.9 mm
Thickness    1.1 mm