POPULAR LECTURES ON SCIENTIFIC SUBJECTS

BY HERMANN VON HELMHOLTZ

TRANSLATED BY E. ATKINSON, Ph.D., F.C.S.

FORMERLY PROFESSOR OF EXPERIMENTAL SCIENCE, STAFF COLLEGE

SECOND SERIES

WITH AN AUTOBIOGRAPHY OF THE AUTHOR

LONGMANS, GREEN, AND CO.

39 PATERNOSTER ROW, LONDON NEW YORK, BOMBAY, AND CALCUTTA 1908

All rights reserved

BIBLIOGRAPHICAL NOTE.

Issued in Silver Library, March 1893; Reprinted July 1895, May 1898, June 1900, December 1903, August 1908.

PREFACE.

The favour with which the first series of Professor Helmholtz’s Lectures has been received would justify, if a justification were needed, the publication of the present volume.

I have to express my acknowledgments to Professor G. Croome Robertson, the editor, and to Messrs. Macmillan, the publishers of ‘Mind,’ for permission to use a translation of the paper on the ‘Axioms of Modern Geometry’ which appeared in that journal.

The article on ‘Academic Freedom in German Universities’ contains some statements respecting the Universities of Oxford and Cambridge to which exception has been taken. These statements were a fair representation of the impression produced on the mind of a foreigner by a state of things which no longer exists in those Universities, at least to the same extent. The reform in the University system, which may be said to date from the year 1854, has brought about so many alterations both in the form and in the spirit of the regulations, that older members of the University have been known to speak of the place as so changed that they could scarcely recognise it. Hence, in respect of this article, I have availed myself of the liberty granted by Professor Helmholtz, and have altogether omitted some passages, and have slightly modified others, which would convey an erroneous impression of the present state of things. I have also on these points consulted members of the University on whose judgment I think I can rely.

In other articles, where the matter is of prime importance, I have been anxious faithfully to reproduce the original; nor have I in any such cases allowed a regard for form to interfere with the plain duty of exactly rendering the author’s meaning.

E. ATKINSON.

Portesbery Hill, Camberley: Dec. 1880.

CONTENTS.

LECTURE PAGE

I. Gustav Magnus. In Memoriam 1

II. On the Origin and Significance of Geometrical Axioms 27

III. On the Relation of Optics to Painting 73

I. Form 78

II. Shade 94

III. Colour 110

IV. Harmony of Colour 124

IV. On the Origin of the Planetary System 139

V. On Thought in Medicine 199

VI. On Academic Freedom in German Universities 237

VII. Hermann von Helmholtz.

An Autobiographical Sketch 266