Letters of John Herschel to Mary Cornwallis Herschel [formerly Power, née Lipscomb] Letters from John Herschel to his wife, giving an account of travels and related matters, as moves between camps on the surveying work for the Great Trigonometrical Survey of India. This set of letters relates to one single period of separation berween the two, in early 1872, during which they agreed to write on alternate days, so that each would contribute a letter at two day intervals. Generally, Herschel's letters are monogrammed 'JH'. The recipient's name is not given. January-April 1872