A biographical appreciation presents paired portraits of two sisters, sketching family background, upbringing, musical and scientific influences, and formative travels in Italy. It traces one sister's intellectual development into a popular astronomical writer—early reading, mathematical study, numerous essays for the Edinburgh Review, and a major History of Astronomy—while also recording the elder sister's life and character. The volume combines personal reminiscence, correspondence, and scholarly appraisal, includes a foreword and a bibliography of articles, and is illustrated with photographs and a portrait bust.