xii CONTENTS 



PAGE 



'On the actual Foundations of Geometry.' (Lecture, 

 Heidelberg, Gottingen Nachrichten, 1868) . . . 254 



' On the Origin and Significance of Geometric Axioms/ 

 Lecture at Heidelberg, translated in Pop. Sclent. Lect., 

 Series II .. . . ... 254 



Note on the Fundamental Notions of Mathematics and 

 Physics ... . 256 



1869. Correspondence with Beltrami 263 



'The Facts of Perception.' Address delivered in 1878 



at the Commemoration of the Foundation of the University 



of Berlin 267 



'On the Origin and Signification of Geometrical Pro- 

 positions.' Reply to Prof. Land, 1878. 



' On the Physiological Action of brief Electrical Shocks 

 in the Interior of extended conducting Masses/ (Heidel- 

 berg Scientific and Medical Society) 268 



' On Electrical Oscillations/ (Heidelberg Society) . 268 

 'On the Aim and the Developments of the Natural 

 4 Sciences/ (Innsbruck Naturforscher-Versammlung) . 268 

 ' On Hay Fever/ Virchow's Archiv .... 268 

 'On Sound Vibrations in the Cochlea/ (Heidelberg 

 Society) 269 



1870. 'On the Laws of Inconstant Electrical Currents in 

 Material Conductors/ (Heidelberg Society) . . . 269 



'On the Theory of Electrodynamics/ Part I : 'On the 

 Motional Equations of Electricity for resting conducting 

 Bodies/ Crelle Journ., LXXII 269 



Call to the Professorship of Physics in Berlin . . 275 



1871. ' On the Origin of the Planetary System/ (Lecture, 

 Heidelberg.) Translated in Pop. Set. Lect., Series II .280 



PROFESSOR OF PHYSICS IN BERLIN, 1871-1888 . . . 281 



1871. 'On the Rate of Transmission of Electrodynamic 

 Effects/ (Berlin Academy) . . . . . . 282 



'In memory of Gustav Magnus/ (Address to the 

 Academy of Sciences, Berlin, translated in Pop. Sci. Lect., 

 Series II) 282 



' Preface and Critical Supplement to the German trans- 

 lation of "J. Tyndall, Fragments of Science," ' 1874 . . 284 



Journey to England 285 



1872. 'On the Theory of Electrodynamics/ (Berlin Academy) 288 



