Letters on Different Subjects in Natural Philosophy, Volume 1 (Letters to a Ger…


The Letters of Euler to a German Princess have acquired over all Europe a celebrity to which the reputation of the Author, the choice and importance of the several subjects, and the clearness of elucidation justly entitle them. They have deservedly been considered as a treasury of science, adapted to the purposes of every common seminary of learning. They may be studied to advantage without much previous elementary knowledge; they convey accurate ideas respecting a variety of objects, highly interesting in themselves, or calculated to excite a laudable curiosity; they inspire a proper taste for the sciences, and for that sound philosophy which, supported by science, and never losing sight of her cautious, steady, methodical advances, runs no risk of perplexing or misleading the attentive student. - Summary by Nicolas de Condorcet (14 hr 8 min)

Chapters

Of Magnitude, or Extension 7:47
Of Velocity 7:07
Of Sound, and Its Velocity 7:52
Of Consonance and Dissonance 6:28
Of Unison and Octaves 8:10
Of Other Consonances 9:14
Of the Twelve Tones of the Harpsichord 13:19
Of the Pleasure Derived from Fine Music 5:55
Compression of the Air 7:23
Rarefaction and Elasticity of the Air 8:16
Gravity of the Air 7:01
Of the Atmosphere, and the Barometer 6:18
Of Air-Guns, and the Compression of Air in Gunpowder 6:43
The Effect Produced by Heat and Cold on All Bodies, and Of, the Pyrometer and T… 5:31
Changes Produced in the Atmosphere by Heat and Cold 7:48
The Cold Felt on High Mountains and at Great Depths Accounted For 7:25
Of Light, and the Systems of Descartes and Newton 6:54
Difficulties Attending the System of Emanation 6:36
A Different System Respecting the Nature of Rays and of Light Proposed 7:31
Of the Propagation of Light 6:42
Digression on the Distances of the Heavenly Bodies, and on the Nature of the Su… 6:15
Elucidations on the Nature of Luminous Bodies, and Their Difference from Opaque… 7:16
How Opaque Bodies Become Visible Newton's System of the Reflection of Rays Prop… 8:34
Examination and Refutation of Newton's System 11:36
A Different Explanation of the Manner in Which Opaque Bodies Illuminated Become… 7:44
Continuation of the Same Subject 8:50
Conclusion: Clearness and Colour of Opaque Bodies Illuminated 9:37
Nature of Colours in Particular 6:28
Transparency of Bodies Relative to the Transmission of Rays 8:32
Of the Transmission of Rays of Light Through Transparent Mediums, and Their Ref… 8:04
Refraction of Rays of Different Colours 7:14
Of the Azure Colour of the Heavens 8:54
Of Rays Issuing from a Distant Luminous Point, and of the Visual Angle 6:34
Of the Assistance Which Judgment Lends to Vision 6:43
Explanation of Certain Phenomena Relative to Optics 7:29
Of Shadow 7:16
Of Catoptrics, and the Reflection of Rays from Plain Mirrors 8:24
Reflection of Rays from Convex and Concave Mirrors Burning Mirrors 8:04
Of Dioptrics 8:36
Continuation of Burning — Glasses, and Their Focus 7:12
Of Vision, and the Structure of the Eye 5:24
Continuation Wonders Discoverable in the Structure of the Eye 6:07
Further Continuation Astonishing Difference Between the Eye of an Animal and th… 6:44
Perfections Discoverable in the Structure of the Eye 4:40
Of Gravity, Considered as a General Property of Body 6:58
Continuation of Specific Gravity 6:55
Terms Relative to Gravity and Their True Import 6:29
Reply to Certain Objections to the Erath's Spherical Figure, Derived from Gravi… 6:17
True Direction and Action of Gravity Relatively to the Earth 6:52
Different Action of Gravity with Respect to Certain Countries and Distances fro… 7:57
Gravity of the Moon 5:33
Discovery of Universal Gravitation by Newton 9:08
Continuation of the Mutual Attraction of the Heavenly Bodies 9:18
Different Sentiments of Philosophers Respecting Universal Gravitation the Attra… 7:04
Power by Which the Heavenly Bodies an Mutually Attracted 4:08
The Same Subject Continued 6:41
The Same Subject Continued 6:37
Motion of the Heavenly Bodies Method of Determining It by the Laws of Universal… 4:56
System of the Universe 6:40
The Same Subject Continued 5:29
Small Irregularities in the Motions of the Planets, Caused by Their Mutual Attr… 5:59
Description of the Flux and Reflux of the Sea 6:45
Different Opinions of Philosophers Respecting the Flux and Reflux of the Sea 6:22
Explanation of the Flux and Reflux, from the Attractive Power of the Moon 5:33
The Same Subject Continued 5:06
The Same Subject Continued 6:17
The Same Subject Continued 6:15
More Particular Account of the Dispute Respecting Universal Gravitation 7:05
Nature and Essence of Bodies or Extension, Mobility, and Impenetrability of Body 7:33
Impenetrability of Bodies 5:40
Of the Motion of Bodies, Real and Apparent 8:16
Of Uniform, Accelerated, and Retarded Motion 12:33
Principal Law of Motion and Rest Disputes of Philosophers on the Subject 8:02
Of the Inertia of Bodies of Powers 7:47
Changes Which May Take Place in the State of Bodies 8:05
System of the Monads of Wolff 8:09
Origin and Nature of Powers 7:11
The Same Subject Principle of the Least Possible Action 7:16
On the Question, are There Any Other Species of Powers? 7:40
Of the Nature of Spirits 5:12
Of the Union Between the Soul and the Body 6:32
Different Systems Relative to This Subject 6:49
Examination of the System of Pre-Established Harmony an Objection to It 7:02
Another Objection 6:32
Of the Liberty of Spirits, and a Reply to Objections Against Liberty 6:40
Tne Same Subject Continued 7:17
Influence of the Liberty of Spirits Upon Events 7:45
Of Events Natural, Supernatural, and Moral 7:03
Of the Question Respecting the Best World Possible; and of the Origin of Evil 8:23
Connexion of the Preceding Considerations with Religion Reply to the Objections… 6:16
The Liberty of Intelligent Beings in Harmony with the Doctrines of the Christia… 5:52
Elucidation Respecting the Nature of Spirits 8:14
The Subject Continued Reflections on the State of Souls After Death 9:03
Considerations on the Action of the Soul Upon the Body, and of the Body Upon th… 8:00
Of the Faculties of the Soul, and of Judgment 8:58
Conviction of the Existence of What We Perceive by the Senses of the Idealists,… 8:27
Refutation of the Idealists 8:22
The Faculty of Perceiving, Reminiscence, Memory, and Attention Simple and Compo… 7:54
Division of Ideas into Clear and Obscure, Distinct and Confused of Distraction 7:07
Of the Abstraction of Notions Notions General and Individual: of Genus and Spec… 8:00
Of Language; Its Nature, Advantages, and Necessity, in Order to the Communicati… 8:39
Of the Perfections of a Language Judgment and Nature of Propositions, Affirmati… 7:59
Of Syllogisms, and Their Different Forms When the First Proposition is Universal 9:31
Different Forms of Syllogisms Whose First Proposition is Particular 9:08
Analysis of Some Syllogisms 7:15
Different Figures and Modes of Syllogisms 11:03
Observations and Reflections on the Different Modes of Syllogism 6:53
Hypothetical Propositions, and Syllogisms Constructed of Them 8:48
Of the Impression of Sensations on the Soul 7:11
Of the Origin and Permission of Evil, and of Sin 9:30
Of Moral and Physical Evil 6:35
Reply to Complaints of the Existence of Physical Evil 6:14
The Real Destination of Man Usefulness and Necessity of Adversity 5:16
Of True Happiness. Conversion of Sinners. Reply to Objections on the Subject 6:32
The True Foundation of Human Knowledge Sources of Truth, and Classes of Informa… 5:29