Letters on Different Subjects in Natural Philosophy, Volume 1 (Letters to a German Princess)
by Leonhard Euler
About this book
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
Chapters (115)
1Of Magnitude, or Extension
2Of Velocity
3Of Sound, and Its Velocity
4Of Consonance and Dissonance
5Of Unison and Octaves
6Of Other Consonances
7Of the Twelve Tones of the Harpsichord
8Of the Pleasure Derived from Fine Music
9Compression of the Air
10Rarefaction and Elasticity of the Air
11Gravity of the Air
12Of the Atmosphere, and the Barometer
13Of Air-Guns, and the Compression of Air in Gunpowder
14The Effect Produced by Heat and Cold on All Bodies, and Of, the Pyrometer and Thermometer
15Changes Produced in the Atmosphere by Heat and Cold
16The Cold Felt on High Mountains and at Great Depths Accounted For
17Of Light, and the Systems of Descartes and Newton
18Difficulties Attending the System of Emanation
19A Different System Respecting the Nature of Rays and of Light Proposed
20Of the Propagation of Light
21Digression on the Distances of the Heavenly Bodies, and on the Nature of the Sun and His Rays
22Elucidations on the Nature of Luminous Bodies, and Their Difference from Opaque Bodies Illuminated
23How Opaque Bodies Become Visible Newton's System of the Reflection of Rays Proposed
24Examination and Refutation of Newton's System
25A Different Explanation of the Manner in Which Opaque Bodies Illuminated Become Visible
26Continuation of the Same Subject
27Conclusion: Clearness and Colour of Opaque Bodies Illuminated
28Nature of Colours in Particular
29Transparency of Bodies Relative to the Transmission of Rays
30Of the Transmission of Rays of Light Through Transparent Mediums, and Their Refraction
31Refraction of Rays of Different Colours
32Of the Azure Colour of the Heavens
33Of Rays Issuing from a Distant Luminous Point, and of the Visual Angle
34Of the Assistance Which Judgment Lends to Vision
35Explanation of Certain Phenomena Relative to Optics
36Of Shadow
37Of Catoptrics, and the Reflection of Rays from Plain Mirrors
38Reflection of Rays from Convex and Concave Mirrors Burning Mirrors
39Of Dioptrics
40Continuation of Burning — Glasses, and Their Focus
41Of Vision, and the Structure of the Eye
42Continuation Wonders Discoverable in the Structure of the Eye
43Further Continuation Astonishing Difference Between the Eye of an Animal and the Artificial Eye, or Camera Obscura
44Perfections Discoverable in the Structure of the Eye
45Of Gravity, Considered as a General Property of Body
46Continuation of Specific Gravity
47Terms Relative to Gravity and Their True Import
48Reply to Certain Objections to the Erath's Spherical Figure, Derived from Gravity
49True Direction and Action of Gravity Relatively to the Earth
50Different Action of Gravity with Respect to Certain Countries and Distances from the Centre of the Earth
51Gravity of the Moon
52Discovery of Universal Gravitation by Newton
53Continuation of the Mutual Attraction of the Heavenly Bodies
54Different Sentiments of Philosophers Respecting Universal Gravitation the Attractionists
55Power by Which the Heavenly Bodies an Mutually Attracted
56The Same Subject Continued
57The Same Subject Continued
58Motion of the Heavenly Bodies Method of Determining It by the Laws of Universal Gravitation
59System of the Universe
60The Same Subject Continued
61Small Irregularities in the Motions of the Planets, Caused by Their Mutual Attraction
62Description of the Flux and Reflux of the Sea
63Different Opinions of Philosophers Respecting the Flux and Reflux of the Sea
64Explanation of the Flux and Reflux, from the Attractive Power of the Moon
65The Same Subject Continued
66The Same Subject Continued
67The Same Subject Continued
68More Particular Account of the Dispute Respecting Universal Gravitation
69Nature and Essence of Bodies or Extension, Mobility, and Impenetrability of Body
70Impenetrability of Bodies
71Of the Motion of Bodies, Real and Apparent
72Of Uniform, Accelerated, and Retarded Motion
73Principal Law of Motion and Rest Disputes of Philosophers on the Subject
74Of the Inertia of Bodies of Powers
75Changes Which May Take Place in the State of Bodies
76System of the Monads of Wolff
77Origin and Nature of Powers
78The Same Subject Principle of the Least Possible Action
79On the Question, are There Any Other Species of Powers?
80Of the Nature of Spirits
81Of the Union Between the Soul and the Body
82Different Systems Relative to This Subject
83Examination of the System of Pre-Established Harmony an Objection to It
84Another Objection
85Of the Liberty of Spirits, and a Reply to Objections Against Liberty
86Tne Same Subject Continued
87Influence of the Liberty of Spirits Upon Events
88Of Events Natural, Supernatural, and Moral
89Of the Question Respecting the Best World Possible; and of the Origin of Evil
90Connexion of the Preceding Considerations with Religion Reply to the Objections of the Philosophical Systems Against Prayer
91The Liberty of Intelligent Beings in Harmony with the Doctrines of the Christian Religion
92Elucidation Respecting the Nature of Spirits
93The Subject Continued Reflections on the State of Souls After Death
94Considerations on the Action of the Soul Upon the Body, and of the Body Upon the Soul
95Of the Faculties of the Soul, and of Judgment
96Conviction of the Existence of What We Perceive by the Senses of the Idealists, Egotists, and Materialists
97Refutation of the Idealists
98The Faculty of Perceiving, Reminiscence, Memory, and Attention Simple and Compound Ideas
99Division of Ideas into Clear and Obscure, Distinct and Confused of Distraction
100Of the Abstraction of Notions Notions General and Individual: of Genus and Species
101Of Language; Its Nature, Advantages, and Necessity, in Order to the Communication of Thought, and the Cultivation of Knowledge
102Of the Perfections of a Language Judgment and Nature of Propositions, Affirmative and Negative, Universal or Particular
103Of Syllogisms, and Their Different Forms When the First Proposition is Universal
104Different Forms of Syllogisms Whose First Proposition is Particular
105Analysis of Some Syllogisms
106Different Figures and Modes of Syllogisms
107Observations and Reflections on the Different Modes of Syllogism
108Hypothetical Propositions, and Syllogisms Constructed of Them
109Of the Impression of Sensations on the Soul
110Of the Origin and Permission of Evil, and of Sin
111Of Moral and Physical Evil
112Reply to Complaints of the Existence of Physical Evil
113The Real Destination of Man Usefulness and Necessity of Adversity
114Of True Happiness. Conversion of Sinners. Reply to Objections on the Subject
115The True Foundation of Human Knowledge Sources of Truth, and Classes of Information Derived from It
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