Popular lectures on scientific subjects. 2nd series

308 Pages·21.406 MB·English

by  Helmholtz H.

mm mt

POPULAR LECTURES
OK
SCIENTIFIC SUBJECTS.
SECOND SERIES.
WORKS BY JOHN TYNDALL, D.C.L LLD. F.R.S.
FRAGMENTS of SCIENCE: a Series of Detached Essays,
Addresses,andReviews. 2vols.crown8vo.Ito.
NEW FRAGMENTS. Crown 8vo. 10s. $d.
LECTURES on SOUND. With Frontispiece of Fog-Syren,
aud203otherWoodcutsandDiagramsintheText. Crown8\o. lus.6d.
HEAT, a MODE of MOTION. With 125 Woodcuts and
Diagraii's. Crown8vo.12s.
LEC1URES on LIGHT, DELIVERED in the UNITED
bTATES in 1872 and 1873. With Portrait, Lithographic Plate, and
59Diagrams. Crown8vo.5*.
ESSAYS on the FLOATING MATTER of the AIR in
RELATION to PUTREFACTION and INFECTION. With 24Wood-
cuts. Crown8vo.7*.6rf.
RESEARCHES on DIAMAGNETISM and MAGNE-
CRYSTALLIC ACTION; including the Question of Diamagnttic
Polarity. Crown8vo.12*.
NOTES of a COURSE of NINE LECTURES on LIGHT,
delivered at the Koyal Institution of Great Britain, 1869. Crown
8vo.1*.6rf.
NOTES of a COURSE of SEVEN LECTURES on ELEC-
TRICAL PHENOMENA and THEORIES, delivered at the Royal
Institutionof Great^Britain,1870. Crown8vo.1*.6rf.
LESSONSinELECTRICITYattheROYAL INSTITUTION,
1875-1876. With58WoodcutsandDiagrams. Crown8vo.2s.6rf.
THE GLACIERS of the ALPS: being a Narrative of
ExcursionsandAscents. AnAccountof theOriginand Phenomenaof
Glaciers, and an Exposition of the Physical Principles to which they
arerelated. With6Illustrations. Crown8vo.6.?.6d.net. 'SilverLibrary'
Edition,3s.6d.
HOURS ofEXERCISE in the ALPS. With 7 Illustrations.
Crown8vo.6*.6d.net. 'SilverLibrary'Edition,3*. Qd.
FARADAYas aDISCOVERER. With2 Portraits. Fcp.8vo.
3s.6rf.
LONGMANS, GREEN,& CO. 39 PaternosterRow, London
NewYork,Bombay,andCalcutta.
POPULAR LECTURES
ON
SCIENTIFIC SUBJECTS
HERMANN VON HELMHOLTZ
TRANSLATED BY
E. ATKINSON, PH.D., F.C.S.
FORMERLY FKOKESSOB OF EXPERIMENTALSCIENCE,8TAJ1? COLLEGE
SECOND SERIES
WITH AN AUTOBIOGRAPHY OF THE AUTHOR
LONGMANS, GEE EN, AND CO.
39 PATERNOSTER ROW, LONDON
NEW YORK, BOMBAY, AND CALCUTTA
1908
All rights reserved
v
A
^>"
BIBLIOGRAPHICAL NOTE.
Issued in Silver Library, March 1893; Reprinted
July1895, May 1898, June 1900, December 1903, August
1908.
PEEFAOB.
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 Pro-
fessor G. Croome Eobertson, 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 ex-
ception has been taken. These statements were a fair
representation ofthe 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
47^42
vi PREFACE.
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 erro-
neous impression of the present state of things. I
have also on these points consulted members of the
University on whosejudgment I think I can rely.
In other articles, where the matter is of prime
importance, I have been anxious faithfully to repro-
duce the original; nor have I in any such cases al-
lowed a regard for form to interfere with the plain
duty ofexactly rendering the author's meaning.
E. ATKINSON.
PeRTEBERY HlLL, CA.MBEELEY:
Dec. 1830.