Instructions
Look for the lyre. It is shaped like a harp with only three strings. Any insignia with this shape is a lyre insignia.
Examine the lyre for a number. Many lyre insignias had a number on or above the lyre that signified what military band in which they played or what unit they were a part.
Look for a lyre surrounded by a wreath. Starting in the 1890s, a number of lyre insignias have wreaths around the lyre.