File talk:Postcard-from-Maxwell-to-Tait.jpg

Is anyone familiar with Maxwell's notation in this picture? Many of the terms in his equations appear to be inside an upside-down square root symbol. Does anyone know what this means? (Or conversely, can anyone recognize the equation he's writing?) Inasilentway (talk) 02:08, 19 October 2011 (UTC)

The sign you are looking for is the older version of the factorial. I am not 100% sure about this but I think Maxwell was writing about the spherical harmonics. Nklohit (talk) 18:13, 28 April 2015 (UTC)