Isidore Singer 
Jewish Encyclopedia [PDF ebook] 
A Descriptive Record of the History, Religion, Literature, and Customs of the Jewish People From the Earliest Times to the Present Day; Aach Apocalyptic Literature

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. In treating of those Jews whose activities have lain outside of distinctively Jewish Spheres, it has been deemed sufficient to give short sketches of their lives with a simple indication of what their contributions have been to their particular fields of labor. Only occasionally, and for reasons of weight, has a departure been made from this policy. A summary of the contributions thus made to the various sciences will be found under the respective headings.