Six Lectures on Light

Six Lectures on Light

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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
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LECTURES ON LIGHT ***

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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 Descartes and the
Rainbow Newton's Experiments on the Composition of Solar Light His
Mistake regarding Achromatism Synthesis of White Light Yellow and
Blue Lights produce White by their Mixture Colours of Natural Bodies
Absorption Mixture of Pigments contrasted with Mixture of Lights
LECTURE II.
Origin of Physical Theories Scope of the Imagination Newton and the
Emission Theory Verification of Physical Theories The Luminiferous
Ether Wave-theory of Light Thomas Young Fresnel and Arago
Conception of Wave-motion Interference of Waves Constitution of
Sound-waves Analogies of Sound and Light Illustrations of
Wave-motion Interference of Sound Waves Optical Illustrations Pitch
and Colour Lengths of the Waves of Light and Rates of Vibration of
the Ether-particles Interference of Light Phenomena which first
suggested the Undulatory Theory Boyle and Hooke The Colours of thin
Plates The Soap-bubble Newton's Rings Theory of 'Fits' Its Explanation
of the Rings Overthrow of the Theory Diffraction of Light Colours
produced by Diffraction Colours of Mother-of-Pearl.
LECTURE III.
Relation of Theories to Experience Origin of the Notion of the
Attraction of Gravitation Notion of Polarity, how generated Atomic
Polarity Structural Arrangements due to Polarity Architecture of
Crystals considered as an Introduction to their Action upon Light
Notion of Atomic Polarity applied to Crystalline Structure
Experimental Illustrations Crystallization of Water Expansion by Heat
and by Cold Deportment of Water considered and explained Bearings
of Crystallization on Optical Phenomena Refraction Double Refraction
Polarization Action of Tourmaline Character of the Beams emergent
from Iceland Spar Polarization by ordinary Refraction and Reflection
Depolarization.
LECTURE IV.
Chromatic Phenomena produced by Crystals in Polarized Light The
Nicol Prism Polarizer and Analyzer Action of Thick and Thin Plates of
Selenite Colours dependent on Thickness Resolution of Polarized
Beam into two others by the Selenite One of them more retarded than

the other Recompounding of the two Systems of Waves by the
Analyzer Interference thus rendered possible Consequent Production of
Colours Action of Bodies mechanically strained or pressed Action of
Sonorous Vibrations Action of Glass strained or pressed by Heat
Circular Polarization Chromatic Phenomena produced by Quartz The
Magnetization of Light Rings surrounding the Axes of Crystals Biaxal
and Uniaxal Crystals Grasp of the Undulatory Theory The Colour and
Polarization of Sky-light Generation of Artificial Skies.
LECTURE V.
Range of Vision not commensurate with Range of Radiation The
Ultra-violet Rays Fluorescence The rendering of invisible Rays visible
Vision not the only Sense appealed to by the Solar and Electric Beam
Heat of Beam Combustion by Total Beam at the Foci of Mirrors and
Lenses Combustion through Ice-lens Ignition of Diamond Search for
the Rays here effective Sir William Herschel's