Copy letter, from Sir John Herschel to Sir Charles Lyell, 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 some of Charles Lyell's writings; further argues that a canal at Suez and/or Darien would have a major effect on European climate due to the effect of ocean currents coming through such canals. 13 October 1866