by Andrew Dickson White
by Lynn Thorndike
by Museum of History and Technology (U.S.)
by Alexander von Humboldt
by Friedrich Dannemann
by Walter Libby
by Lynn Thorndike
by A. C. (Albert Charles) Seward
by Edward Huntington Williams, Henry Smith Williams
by Edward Huntington Williams, Henry Smith Williams
by Edward Huntington Williams, Henry Smith Williams
by Edward Huntington Williams, Henry Smith Williams
by William Whewell
by Edward Huntington Williams, Henry Smith Williams
by James J. (James Joseph) Walsh
by Friedrich Dannemann
by Friedrich Dannemann
by Arthur Selwyn-Brown, Garrett Putman Serviss
by John F. W. (John Frederick William) Herschel
by John Fiske
by Friedrich Dannemann
by William Whewell
by Thomas Henry Huxley
by Sir E. Ray (Edwin Ray) Lankester
by Wilhelm Bölsche
by Wilhelm Bölsche