The famous letter of the renowned astronomer Caroline Herschel to Mary Sommerville mentions some of her "lost" and "forgotten" sister scientists of the past. The book tells the lives of these twenty female scientists, with specific attention to astronomers and mathematicians, spanning over a period of about 4000 years. Each of these biographies is organized as a kind of "personal file" which includes a section setting the life in the appropriate historical background, her main works, some curious facts, and some citations about her. This book tells the lives of twenty female scientists, principally astronomers and mathematicians, who made very important contributions to the development of science yet for too long remained forgotten. For each of these ?long lost sisters of science?, to use Caroline Herschel?s phrase, the author has organized a form of personal file that places the subject?s life within its historical context, outlines her main works, highlights some curious and interesting facts, and presents comments from contemporaries and others. The book reaches back more than 4000 years, to En HeduAnna, the Akkadian princess, who was one of the first recognized female astronomers, and includes such luminaries as Hypatia of Alexandra, Hildegard of Bingen, Elisabetha Hevelius, and Maria Gaetana Agnesi, through to Mary Somerville and Caroline Herschel herself. The book will be of interest to all who wish to learn more about the women from antiquity to the nineteenth century who played such key roles in the history of astronomy and science despite living and working in largely male-dominated worlds.