Copy of letter, from Sir John Herschel to Mary Somerville, dated at Collingwood Copy of letter, copied as part of the correspondence project led by Colonel John Herschel FRS following the death of his father. Comments on the political change within Italy. Answers questions about spectrum analysis, spectra of nebulae, and [solar] 'willow leaves.' Says the view of universe as a collection of billiard balls is problematic. Includes postscript from John Frederick William Herschel's daughter Bella describing family events. 11 April 1865