Copy of draft letter, from Sir John Herschel to Warren de La Rue, dated at Collingwood Copy of draft letter, copied as part of the correspondence project led by Colonel John Herschel FRS following the death of his father. Returns the certificates duly signed and also Angelo Secchi's letter, which he was pleased to see. Elaborates on the possible causes of James Nasmyth's 'willow leaves.' 31 January 1865