Copy letter, from Sir John Herschel to George Gabriel Stokes, dated at Collingwood Copy of a letter, copied as part of the correspondence project led by Colonel John Herschel FRS following the death of his father. Comments on George Gabriel Stokes's ideas [see George Gabriel Stokes's 1856-6-27] about the nature of fluorescence. Asks for strong horseshoe magnets from Royal Society [of London] to try to solve the problem of 'Mahomet's coffin.' 1 July 1856