Keywords: Broom bridge plaque.jpg en Somewhat vandalized plaque on Brougham Bridge in Central Dublin commemorating Hamilton's invention of w quaternions <br> The plaque says <big>Here as he walked by <br> on the 16th of October 1843 <br> Sir William Rowan Hamilton <br> in a flash of genius discovered <br> the fundamental formula for <br> quaternion multiplication <br> i<sup>2</sup> j<sup>2</sup> k<sup>2</sup> i j k 1 <br> cut it on a stone of this bridge </big> Transferred from http //en wikipedia org en wikipedia; transferred to Commons by User Premeditated Chaos using http //tools wikimedia de/~magnus/commonshelper php CommonsHelper 2005 05 Original uploader was Wisher at http //en wikipedia org en wikipedia Released into the public domain by the author <gallery>File Quaternion Plaque on Broom Bridge jpg</gallery> 53 372997 -6 3000128 region IE en wikipedia Wisher Original upload log page en wikipedia Broombridge2 jpg 2006-03-05 21 14 Wisher 1536×1024× 207614 bytes <nowiki>Author - wisher Photo of the plaque on Brougham Bridge in Central Dublin Photo taken mid May 2005 </nowiki> Mathematical formulas Plaques in Dublin 1843 in science 16 October William Rowan Hamilton 2005 in Dublin 200505 Dublin May 2005 in Ireland 200505 Dublin |