CONTENTS. 



tBCTTTBE PAQS 



I. GUSTAV MAGNVS. IN MEMORIAM . , . i 



II. ON THE ORIGIN AND SIGNIFICANCES OF GEOMETRICAL 



AXIOMS 27 



IIT. ON THE RELATION OF OPTICS TO PAINTING . . 73 



i. Form 7?, 



H. Shade 94 



in. Colour . . . . . . . . .110 



IV. Harmony of Colour 124 



IV. ON THE ORIGIN OF THE PLANETARY SYSTEM . .139 



V. ON THOUGHT IN MEDICINE 199 



VL ON ACADEMIC FREEDOM IN GERMAN UNIVERSITIES . 237 



VII. HERMANN VON HELMHOLTZ. Au AUTOBIOGRAPHICAL 



SKBICH . , 206 



