Letters on Different Subjects in Natural Philosophy, Volume 1 (Letters to a German Princess)

Author(s)

Leonhard Euler

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

Of Magnitude, or Extension
Of Velocity
Of Sound, and Its Velocity
Of Consonance and Dissonance
Of Unison and Octaves
Of Other Consonances
Of the Twelve Tones of the Harpsichord
Of the Pleasure Derived from Fine Music
Compression of the Air
Rarefaction and Elasticity of the Air
Gravity of the Air
Of the Atmosphere, and the Barometer
Of Air-Guns, and the Compression of Air in Gunpowder
The Effect Produced by Heat and Cold on All Bodies, and Of, the Pyrometer and Thermometer
Changes Produced in the Atmosphere by Heat and Cold
The Cold Felt on High Mountains and at Great Depths Accounted For
Of Light, and the Systems of Descartes and Newton
Difficulties Attending the System of Emanation
A Different System Respecting the Nature of Rays and of Light Proposed
Of the Propagation of Light
Digression on the Distances of the Heavenly Bodies, and on the Nature of the Sun and His Rays
Elucidations on the Nature of Luminous Bodies, and Their Difference from Opaque Bodies Illuminated
How Opaque Bodies Become Visible Newton's System of the Reflection of Rays Proposed
Examination and Refutation of Newton's System
A Different Explanation of the Manner in Which Opaque Bodies Illuminated Become Visible
Continuation of the Same Subject
Conclusion: Clearness and Colour of Opaque Bodies Illuminated
Nature of Colours in Particular
Transparency of Bodies Relative to the Transmission of Rays
Of the Transmission of Rays of Light Through Transparent Mediums, and Their Refraction
Refraction of Rays of Different Colours
Of the Azure Colour of the Heavens
Of Rays Issuing from a Distant Luminous Point, and of the Visual Angle
Of the Assistance Which Judgment Lends to Vision
Explanation of Certain Phenomena Relative to Optics
Of Shadow
Of Catoptrics, and the Reflection of Rays from Plain Mirrors
Reflection of Rays from Convex and Concave Mirrors Burning Mirrors
Of Dioptrics
Continuation of Burning — Glasses, and Their Focus
Of Vision, and the Structure of the Eye
Continuation Wonders Discoverable in the Structure of the Eye
Further Continuation Astonishing Difference Between the Eye of an Animal and the Artificial Eye, or Camera Obscura
Perfections Discoverable in the Structure of the Eye
Of Gravity, Considered as a General Property of Body
Continuation of Specific Gravity
Terms Relative to Gravity and Their True Import
Reply to Certain Objections to the Erath's Spherical Figure, Derived from Gravity
True Direction and Action of Gravity Relatively to the Earth
Different Action of Gravity with Respect to Certain Countries and Distances from the Centre of the Earth
Gravity of the Moon
Discovery of Universal Gravitation by Newton
Continuation of the Mutual Attraction of the Heavenly Bodies
Different Sentiments of Philosophers Respecting Universal Gravitation the Attractionists
Power by Which the Heavenly Bodies an Mutually Attracted
The Same Subject Continued
The Same Subject Continued
Motion of the Heavenly Bodies Method of Determining It by the Laws of Universal Gravitation
System of the Universe
The Same Subject Continued
Small Irregularities in the Motions of the Planets, Caused by Their Mutual Attraction
Description of the Flux and Reflux of the Sea
Different Opinions of Philosophers Respecting the Flux and Reflux of the Sea
Explanation of the Flux and Reflux, from the Attractive Power of the Moon
The Same Subject Continued
The Same Subject Continued
The Same Subject Continued
More Particular Account of the Dispute Respecting Universal Gravitation
Nature and Essence of Bodies or Extension, Mobility, and Impenetrability of Body
Impenetrability of Bodies
Of the Motion of Bodies, Real and Apparent
Of Uniform, Accelerated, and Retarded Motion
Principal Law of Motion and Rest Disputes of Philosophers on the Subject
Of the Inertia of Bodies of Powers
Changes Which May Take Place in the State of Bodies
System of the Monads of Wolff
Origin and Nature of Powers
The Same Subject Principle of the Least Possible Action
On the Question, are There Any Other Species of Powers?
Of the Nature of Spirits
Of the Union Between the Soul and the Body
Different Systems Relative to This Subject
Examination of the System of Pre-Established Harmony an Objection to It
Another Objection
Of the Liberty of Spirits, and a Reply to Objections Against Liberty
Tne Same Subject Continued
Influence of the Liberty of Spirits Upon Events
Of Events Natural, Supernatural, and Moral
Of the Question Respecting the Best World Possible; and of the Origin of Evil
Connexion of the Preceding Considerations with Religion Reply to the Objections of the Philosophical Systems Against Prayer
The Liberty of Intelligent Beings in Harmony with the Doctrines of the Christian Religion
Elucidation Respecting the Nature of Spirits
The Subject Continued Reflections on the State of Souls After Death
Considerations on the Action of the Soul Upon the Body, and of the Body Upon the Soul
Of the Faculties of the Soul, and of Judgment
Conviction of the Existence of What We Perceive by the Senses of the Idealists, Egotists, and Materialists
Refutation of the Idealists
The Faculty of Perceiving, Reminiscence, Memory, and Attention Simple and Compound Ideas
Division of Ideas into Clear and Obscure, Distinct and Confused of Distraction
Of the Abstraction of Notions Notions General and Individual: of Genus and Species
Of Language; Its Nature, Advantages, and Necessity, in Order to the Communication of Thought, and the Cultivation of Knowledge
Of the Perfections of a Language Judgment and Nature of Propositions, Affirmative and Negative, Universal or Particular
Of Syllogisms, and Their Different Forms When the First Proposition is Universal
Different Forms of Syllogisms Whose First Proposition is Particular
Analysis of Some Syllogisms
Different Figures and Modes of Syllogisms
Observations and Reflections on the Different Modes of Syllogism
Hypothetical Propositions, and Syllogisms Constructed of Them
Of the Impression of Sensations on the Soul
Of the Origin and Permission of Evil, and of Sin
Of Moral and Physical Evil
Reply to Complaints of the Existence of Physical Evil
The Real Destination of Man Usefulness and Necessity of Adversity
Of True Happiness. Conversion of Sinners. Reply to Objections on the Subject
The True Foundation of Human Knowledge Sources of Truth, and Classes of Information Derived from It