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Title: Six Lectures on Light
Delivered In The United States In 1872-1873

Author: John Tyndall

Release Date: November 10, 2004 [EBook #14000]

Language: English

Character set encoding: ASCII

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SIX LECTURES ON LIGHT

DELIVERED IN THE UNITED STATES
IN
1872-1873

BY

JOHN TYNDALL, D.C.L., LL,D., F.R.S.

LATE PROFESSOR OF NATURAL PHILOSOPHY IN THE
ROYAL INSTITUTION OF GREAT BRITAIN

[Illustration: Sir Thomas Laurence PRA Pinx

Henry Adlarc. Sc.

Signature: Thomas Young]

London: Longmans & Co.

_SIXTH IMPRESSION_

LONGMANS, GREEN, AND CO.

39 PATERNOSTER ROW, LONDON

NEW YORK AND BOMBAY

1906

PREFACE TO THE FOURTH EDITION.

In these Lectures I have sought to render clear a difficult but
profoundly interesting subject. My aim has been not only to describe
and illustrate in a familiar manner the principal laws and phenomena
of light, but to point out the origin, and show the application, of
the theoretic conceptions which underlie and unite the whole, and
without which no real interpretation is possible.

The Lectures, as stated on the title-page, were delivered in the
United States in 1872-3. I still retain a vivid and grateful
remembrance of the cordiality with which they were received.

My scope and object are briefly indicated in the 'Summary and
Conclusion,' which, as recommended in a former edition, might be, not
unfitly, read as an introduction to the volume.

J.T.

ALP LUSGEN: _October_ 1885.

CONTENTS.

LECTURE I.

Introductory
Uses of Experiment
Early Scientific Notions
Sciences of Observation
Knowledge of the Ancients regarding Light
Defects of the Eye
Our Instruments
Rectilineal Propagation of Light
Law of Incidence and Reflection
Sterility of the Middle Ages
Refraction
Discovery of Snell
Partial and Total Reflection
Velocity of Light
Roemer, Bradley, Foucault, and Fizeau
Principle of Least Action