Quaternion Eagle
Unofficial coat of arms of the Holy Roman Empire / From Wikipedia, the free encyclopedia
The Quaternion Eagle (German: Quaternionenadler; Italian: Aquila Quaternione), also known as the Imperial Quaternion Eagle (German: Quaternionen-Reichsadler)[1][2] or simply Imperial Eagle (German: Reichsadler),[lower-alpha 1] was an informal coat of arms of the Holy Roman Empire.
Introduced around 1510 by Hans Burgkmair, the Quaternion Eagle mixed two pre-existing concepts: the Imperial Quaternions and the Imperial Eagle (double-headed eagle).[lower-alpha 1]