ILLUSTRATIONS 



PAGE 

 A SAND-STORM ON THE MOJAVE DESEHT 17 



THOMAS YOUNG 195 



HANS CHRISTIAN OERSTED -| 



DOMINIQUE FRANCOIS ARAGO 



J- 201 

 AUGUSTIN JEAN FRESNEL 



JAMES CLERK MAXWELL , 



MICHAEL FARADAY 211 



JAMES PRESCOTT JOULE ^ 



WILLIAM THOMSON (LORD KELVIN) 



1" 219 

 JULIUS ROBERT MAYER 





JOHN TYNDALL 



HERMANN LUDVVIG FERDINAND HELMHOLTZ 237 



JOHN DALTON 254 



JOSEPH LOUIS GAY-LUSSAC 257 



JOHAN JAKOIJ BEKZELIUS 261 



JUSTUS TON LIEBIG . . ~. 267 



ROBERT WILLIAM BUNSEN 277 



GUSTAV ROBERT KIIICHHOFF 279 



LOUIS JACQUES MANDE DAGUERRE 281 



JOHN W. DRAPER 285 



ERASMUS DARWIN 290 



JEAN BAPTISTE DE LAMARCK 294 



ETIENNE GEOFFROY SAINT-HILAIHE 299 



CHARLES ROBERT DARWIN 304 



ALFRED RUSSELL WALLACE 308 



THOMAS HENRY HUXLEY 311 



ASA GRAY 314 



ERNEST HAECKEL 319 



MARIE FRANCOIS XAVIER BICHAT 323 



WILLIAM HYDE WOLLASTON 326 



MATTHIAS JAKOB SCHLEIDEN 330 



KARL ERNST VON BAER 333 



JOHANNES MULLER 337 



WILLIAM BENJAMIN CARPENTER 339 



MAX SCHULTZE 341 



HUGO VON MOTH- 344 



JEAN BAPTISTE DUMAS 346 



vii 



