Determination by means of the pendulum of the acceleration produced by gravity. This acceleration is independent of the nature of the body.
Remark that the formulæ for the motion of oscillation apply to the comparison of forces of any kind, that may be regarded as constant and parallel to themselves in all positions of the oscillating body.
Identity of gravity and universal attraction.
Measure of weights. Balance. Conditions to be attended to in making it. Absolute sensibility; proportional sensibility. Method of double weighing. Details of the precautions necessary in order to obtain an exact weight.
Different States of Bodies. Hydrostatics.
Solids. Cohesion. Transmission of external pressures.
Elasticity. The true laws of elasticity are unknown. Empirical laws in certain simple cases, and for a very small action. Elasticity of compression, extension, torsion. Experimental determination of the co-efficients of elasticity. Limits of elasticity. Limits of tenacity.
Ductility. Temper. Cold hammering. Annealing.
Liquids. Fluidity. Viscosity. Physical laws which form the basis of hydrostatics:—1othe transmission of external pressures is equal in all directions; 2othe pressure exercised in the interior of a liquid upon an element of a surface is normal to that element, and independent (as to amount) of its direction. These principles are demonstrated by the experimental verification of the consequences drawn from them.
Application to heavy liquids. Free surface, and surfacede niveau. Pressure upon the parts of the containing vessel, and upon the bottom in particular; hydrostatic paradox; verificatory experiments. Haldat’s apparatus. Hydrostatic press.
Application to immersed or floating bodies (principle of Archimedes;) verificatory experiments. (In treating of the equilibrium of floating bodies, the conditions of stability are not gone into.)
Superposed liquids.
Communicating vessels. Water level. Spirit level; its use in instruments.
Densities of solids and liquids. Anemometers.
Compressibility of liquids. Piezometer. Correction due to the compressibility of the solid envelop.
Gas. Expansibility. Other properties common to liquids and gases. Principle of the equal transmission of pressures in all directions. Weight of gases. Pressure due to weight (principle of Archimedes.) Weight of body in air and in vacuum. Aerostation.
Superposed liquids and gases.
Communicating vessels. Barometer.
Detailed construction of barometer. Barometers of Fortin, Gay-Lussac, Bunten. Indication of the corrections necessary.
Mariotte’s law. Regnault’s experiments.
Manometer with atmospheric air—with compressed air. Bourdon’s manometer.
Law of the mixture of gases.
Air pump. Condensing pump.
Primary Notions of Hydrodynamics.
Toricelli’s principle. Mariotte’s vessel and syphon. Uniform flow of liquids. The same of gases.
Molecular Phenomena.
Cohesion of liquids. Adhesion of liquids to solids. Capillary phenomena. Apparent attractions and repulsions of floating bodies.
Adhesion of drops.
Molecular actions intervene as disturbing forces in the phenomena of the equilibrium and motion of liquids.
HEAT.
EFFECTS OF HEAT ON BODIES.
Lessons 6–9.Generalities.
General effects. Arbitrary choice of one of these effects to define the thermometric condition of a body. Conventional adoption of a thermometer. Definition of temperature.
Dilating Effects.
Definition of the co-efficients of linear, superficial, and cubic dilatation. Approximate relation between the numerical values of these three co-efficients. The value of the co-efficient of dilatation depends upon the thermometric substance and the temperature selected as the zero point. It becomes nearly independent of the zero point when the co-efficient is very small.
Relation between volume, density, and temperature. Linear dilatation of solid bodies. Ramsden’s instrument. Cubical dilatation of liquids. Dulong and Petit’s experiments on mercury. Discussion. Regnault’s experiments.
Cubical dilatation of solids and of other liquids when that of mercury is given.
Relations between the volume, density, and elasticity of a gas, and its temperature.
Cubical dilatation of gases. Experiments of Gay-Lussac, Rudberg, and M. Regnault. Advantage of varying the methods of experimenting in these delicate researches.
Methods based upon the changes of volume under a constant pressure, and upon the changes of pressure for a constant volume.
The disagreement of these two methods is due to deviations from the law of Mariotte.
The constancy of the co-efficients of dilatation previously defined is only approximately true.
Necessity of employing two different co-efficients of dilatation according as consideration is being had to the variations of volume to a given pressure, or of pressure to a given volume.
Empirical formulæ for the dilatation of liquids.
Graphical constructions.
Lesson 10.Thermometers.
Construction of thermometers. Mercurial thermometer. Details of construction. Fixed points. Different scales; their relation. Arbitrary scales.Change which takes place in the zero point. Different precautions to be observed in using the mercurial thermometer.
General want of comparability of mercurial thermometers with tubes of different material.
Air thermometers. They are comparable with one another within the limits of the errors of experiment, whatever the nature of the tube employed. This property entitles the air thermometer to a preference for all accurate measures. Comparison of the air and mercurial thermometers.
THERMOSCOPE, DIFFERENTIAL THERMOMETER, PYROMETERS, BREGUET’S THERMOMETER.
Lessons 11–13.Changes of State produced by Heat.
Exposition of the phenomena which accompany the liquefaction of solids and the solidification of liquids. Constancy of the temperature whilst the phenomenon is going on.
Sudden melting and freezing. Persistance of the liquid state beneath the melting point.
Influence of pressure.
Exposition of the phenomena which accompany the conversion of liquids or solids into vapor, and the inverse passage from the gaseous to the liquid or solid state. Constancy of the temperatures whilst the phenomenon is going on.
Influence of pressure.
Phenomena of ebullition in free space. Augmentation of the temperature and pressure in a confined space. Papin’s digester.
Properties of vapors in spaces and in gases. Saturated vapors. Their tension does not depend upon the space which they occupy, but only upon their temperature.
Effects of a diminution or increase of pressure without change of temperature; the same without change of pressure. Effects of lowering the temperature in a limited region of space occupied by vapor.
Tension of a saturated vapor at the boiling point of its liquid.
Measure of the tensions of the vapor of water. Experiments of Dalton, Gay-Lussac, Dulong, and Arago, and of M. Regnault.
Tables of the tensions of steam. Empirical formulæ. Graphical constructions.
It is assumed that non-saturated vapors are subject to the same laws as gases.
APPLICATIONS. CORRECTION OF THE BOILING-POINT IN THE CONSTRUCTION OF THERMOMETERS. BAROMETRICAL THERMOMETERS.
Lessons 14–16.Various Applications of the Laws previously established.
A phenomenon can not always be separated from the accessory phenomena which concur with it in producing the final result. Necessity of corrections to render complex results comparableinter se.
Density of solids when regard is had to the temperature and weight of the gases displaced by them.
Precautions to be attended to in the experiments. Empirical formulæ for thedensity of liquids. Maximum density of water. The temperature corresponding to the maximum must be determined graphically, or by interpolation.
Corrections for measures of capacity, for barometric measures.
The uncertainty of the corrections can not, in any considerable degree, affect the densities of solids and liquids.
Density of gases. Biot and Arago’s experiments. Special difficulties of the question. The uncertainty of the corrections may sensibly affect the results. Regnault’s method.
The same method may be applied to the determination of the co-efficient of dilatation for gases.
Density of vapors. Definition founded on the hypothetical application of the same laws to gases and vapors. Formulæ. Experimental method of Gay-Lussac and of Dumas. Corrections. Comparison of the two methods. Necessity of conducting the experiments at a distance from the saturation point. Latour’s experiments. Relations between the weight and volume of a gas, and its temperatures; between the weight and volume of a gas mixed with vapors, and its temperature. Various problems.
Hygrometry. Chemical hygrometry. Hygrometry by the dew-point. Psychrometry.
PROPAGATION OF HEAT.
Lessons 17–18.Propagation at a Distance.
Rapid propagation of heat at a distance, in vacuum, in gases, in certain liquid or solid mediums. Experiments which establish this.
Rays of heat. Velocity of propagation. Intensity of heat received at a distance. Intensity of heat received or emitted obliquely. Emitting power, power of absorption, reflection, diffusion. The emitting and absorbing power are expressible by the same number in terms of their proper units respectively.
Analysis of calorific radiations by absorption. Different effects of deathermanous or thermochroic medium. Different influences of increasing thicknesses of the combination of different mediums. Radiations proceeding from different sources, various effects of different mediums on these radiations.
The calorific radiations emanating from different sources, have all the characters of differently colored heterogeneous rays of light.
THEORY OF RADIATION AND OF THE DYNAMICAL EQUILIBRIUM OF TEMPERATURES. APPARENT REFLECTION OF COLD.
Lesson 19.Law of Cooling.
Definition of the rate of cooling. Many causes may conspire in the cooling of a body.
Cooling in space. Newton’s law only an approximation. Experimental investigation of the true law. Method to be followed in this investigation. The velocity of cooling is not adatumdirectly observable. It must be deduced provisionally from an empirical relation between the temperature and the time. Preliminary experiments. Course of the definitive experiments. Elementary experimental laws.
Hypothetical form of the function which expresses the velocity of cooling. To determine by means of the preceding experimental laws the unknown formof the function which expresses the law of radiation. Relation between the temperatures and the times. This relation only contains data immediately observable, and may be verifiedà posteriori.
The contents which enter into the preceding relation depend upon thermometric constants and the nature of the radiating surface.
The contact of a gas modifies the law of cooling.
Lessons 20–21.Propagation by Contact.
Slow propagation of heat in the interior of bodies, in solids, liquids, and gases. Confirmatory experiments. Hypothesis of partial radiation. Theoretical law resulting from this hypothesis upon the decrease of temperatures in a solid limited by two indefinite parallel planes maintained at constant temperatures. Determination of the co-efficient of conductibility by the experimental realization of these conditions. This experiment determines a numerical value of the co-efficients; it is not of a nature to serve as a check upon the theoretical principles. Enunciation of the law resulting from the same theoretical principles upon the decrease of temperatures in a thin bar heated at one end.
CALORIMETRY.
Lessons 22–23.Specific Heats.
Comparison of the quantities of heat. The quantities of heat are not proportioned to the temperatures. Definitions of the unity of heat. General method of mixtures to estimate the quantities of heat. Experimental precautions and corrections.
Application of the general method of mixtures. Specific heats of solids and liquids. Law of the specific heat of atoms. Heat absorbed by expansion, restored by the compression of bodies. Experiments on gases. Specific heats of gases under constant pressure. Measure of specific heats of gases under constant pressure. Special difficulties of the question. Succinct indication of one of the methods. Specific heats to a constant volume.
Lesson 24.Latent Heat.
Component heat of liquids absorbed into thelatentstate during fusion, restored to thefreestate during solidification.
Influence of the viscous state. Latent heat of ice. Ice calorimeter; its defects.
Component heat of vapors, absorbed into the latent state during vaporization, restored to the free state during condensation. Measure of the latent heat of vapors. Regnault’s experiments.
Empirical laws on the latent heat of vaporization.
Applications of Calorimetry.
Means of producing heat or cold; 1, by changes in density; 2, by changes of state. Freezing mixtures. Vaporization of liquids. Condensation of vapors.
Steam-boilers. Warming by hot air and hot water. Various problems. Sensations produced by a jet of vapor.
Different physical and chemical sources of heat; percussion, friction, chemical combinations, animal heat, natural heat of the globe, solar heat, &c. It will beremarked that mechanical work may become a source of heat, and heat a source of mechanical work.
STATICAL ELECTRICITY.—MAGNETISM.—STATICAL ELECTRICITY.
Lessons 25–27.
General phenomena. Distinction of bodies into conductors and non-conductors. Distinction of electricity into two kinds. Separation of the two electricities by friction. Hypothesis of electric fluids. Effects of vacuum of gases and vapors of points. Electrical attractions and repulsions. Electrization by influence. Case where the influenced body is already electrized. Sparks; power of points. Electrization by influence preceding the motion of light bodies.
Electroscopes.
Electrical machines of Van-Marum, Nairne, Armstrong.
Condenser. Accumulation of electricity upon its surface. Leyden jar. Batteries. Electrical discharges. Effects of electricity.
Condensing electroscope. Electrophorus.
Velocity of statical electricity.
Atmospherical electricity. Phenomena observed with a serene sky. Electricity of clouds. Storms. Lightning. Thunder. Effects of thunder. Return-shock. Lightning conductor.
Different sources of statical electricity.
MAGNETISM.
Lessons 28–30.
Natural magnets. Action upon iron and steel. Artificial magnets. The attractive action appears as if it were concentrated about the extremities of magnetic bars. First idea of poles.
Direction of a magnetized bar under the earth’s action. Reciprocal action of the poles of two magnets. Names given to the poles.
Phenomena of influence. Action of a magnet upon a bar of soft iron; upon a bar of steel. Coercive force. Effects of the rupture of a magnetized bar. Theoretical ideas on the constitution of magnets. More precise definition of the poles.
Action of the earth upon a magnet. The earth may be considered as a magnet. Its action may be destroyed by means of a magnet suitably placed. Astatic needles. The magnetic action of the earth is equivalent to acouple. Three constants define the couple of terrestrial action. Declination. Inclination. Intensity. Measure of the declination; of the inclination.
Magnetic metals. Influence of hammering, tempering, &c. Methods of magnetizing. Saturation. Loss of magnetism. Influence of heat. Magnetic lines. Armatures.
Magnetization by the earth’s influence. Means of determining the magnetic state of a body.
Measure of Magnetism and Electricity.
Lessons 31–32.
Coulomb’s balance. Distribution of magnetism on a magnetized bar; distributionof electricity at the surface of isolated conductors. Comparative discussion of the conditions of the two problems and the methods of experiment.
Laws of the magnetic attractions and repulsions. Law of electric attractions and repulsions. Comparative discussion of the conditions of the two problems, and the methods of experiment.
Determination of the law of magnetic attractions and repulsions by the method of oscillations.
Comparison of the magnetic intensity at different points of the earth’s surface.
Lessons 33–34.Revision.
Considerations on the totality of the subjects of the course.
SECOND YEAR.
DYNAMICAL ELECTRICITY.—GALVANISM.
Lessons1–2.
Chemical sources of electricity. Experimental proofs. Arrangement devised by Volta to accumulate, at least in part, at the extremities of a heterogeneous conductor the electricity developed by chemical actions.
Pile. Tension at the two isolated extremities; at one single isolated extremity; at the two extremities reunited by a conductor. Continuous current of electricity. Poles. Direction of the current, &c.
Various modifications of the pile of Volta. Woollaston’s pile, Münch’s pile, &c. Dry piles; their application to the electroscope.
Principal effects of electricity in motion, and means of making the currents perceptible. Experiment of Oersted. Galvanoscopes.
Currents produced by heat in heterogeneous circuits. Thermo-electric piles. Thermometric graduation of thermo-electric piles.
Currents produced by the sources of statical electricity.
PROPERTIES OF CURRENTS.
Lesson 3.1.Chemical Actions.
Definitions. Phenomena of decomposition and transference. Reaction of the elements transferred upon electrodes of different kinds.
Principles of electrotyping.
Causes of the variation of the current in ordinary piles; means of remedying this; Daniell’s pile. Bunsen’s pile.
Lessons 4–8.2.Mechanical Properties.
Reciprocal actions of rectilinear or sinuous currents parallel or inclined. Reaction of a current on itself.
Reciprocal actions of helices or solenoids. Continuous rotation of currents by their mutual action; by reaction. Analogy of magnets and solenoids. Electro-dynamical theory of magnetism. Action of magnets upon currents and solenoids. Action of currents upon magnets. Experiments of Biot and Savart. Continual rotation of a current by a magnet; of a magnet by a magnet.
Action of the earth upon currents; it acts as a rectilinear current directed from east to west, perpendicularly to the magnetic meridian.
Continual rotation of a current by the action of the earth.
Astatic conductors.
Lessons 9–10.3.Magnetic Properties.
Action of an interposed conductor upon iron filings.
Electro-magnets. Magnetization temporary or permanent. Principles of the electric telegraph. Electrometers. Reference to diamagnetic phenomena.
4.Electro-motive Properties.
Phenomena of induction by currents, by magnets. Phenomena of magnetism in motion. Induction of a current upon itself.
Induction of different orders.
Interrupted currents. Clarke’s machine.
Lesson 11.5.Calorific Properties.
Influence of the nature of the interposed conductor; of its ; of the intensity of the current. Unequal temperatures at the different junctions of a heterogeneous circuit.
6.Luminous Properties.
Incandescence of solid conductors. Spectrum of the electric light. Voltaic arc. Transfer of ponderable matter. Action of the magnet upon the Voltaic arc.
7.Physiological Action of Currents.
Some words on this subject. Muscles and nerves. Actions of discontinuous currents. Reotomic contrivances.
Reometry.
Compass of sines, of tangents. Experimental graduation of galvanometers.
The dynamical intensity of a current diminishes when the length of a current increases. Reostat.
Laws of the dynamical intensity of a current in a homogeneous circuit. Reduced length and resistance of a circuit. Specific co-efficients of resistance. Laws of the dynamic intensity of a current in a heterogeneous circuit.
The intensity of currents is in the inverse ratio of the total reduced length, and proportional to the sum of the electromotive forces. Formula of the pile. Discussion of the case of hydro-electric piles—thermo-electric piles. Conditions for the construction of a pile, with reference to the effects to be produced. Conditions for the construction of a galvanometer with reference to its intended application.
Laws of secondary currents in the simplest cases. The chemical intensity of a current is proportional to its dynamical intensity.
ACOUSTICS.
Lessons 12–15.
Noise, sound, quality of the sound, pitch, intensity,timbre. A state of vibration in a solid, liquid, or gaseous body is accompanied with the production of sound.
The pitch depends on the number of vibrations. Unison. Instruments forcounting the vibrations:—1st. Graphic method. 2nd. Toothed wheels. 3rd. Lever. Feeling of concord. Musical scale. Gamut. Limit of appreciable sounds.
Study of vibrating motions in solids. Vibrating cords. Vibrations transversal, longitudinal. Experimental laws. Sonometer.
Spontaneous division of a cord into segments. Fundamental sounds. Harmonic sounds.
Straightand curved rods. Transversal and longitudinal vibrations. Experimental laws. Division into segments. Nodes. Ventral segments. Membranes.
Plane and curved plates. The vibrations divide them into “concamerations.” Nodal lines. Harmonic sounds.
Study of the vibrations in liquids and in gases.
Theoretical ideas upon the propagation of a vibratory motion in indefinite elastic media, on an indefinite cylindrical tube. Waves of condensation of dilatation. Progressive nodes and ventral divisions. Laws of the intensities of sound. Direct measure of the velocity of the propagation of sound in water. Measure of the velocity of the propagation of sound in air. Formulæ without demonstration. Comparison of the formulæ with experiment.
Sonorous waves reflected in an indefinite medium.
Fixed nodes and ventral divisions. Sonorous waves reflected in closed and open tubes. Fixed nodes and ventral divisions; the vibratory state and density thereat.
Series of sounds afforded by the same tube. Effect of holes.
Sonorous reflected waves in rods. Series of sounds afforded by the same rod vibrating longitudinally. Indirect measure of the velocity of sound in gases, liquids, and solids.
Experiments on the communication of vibrating motion in heterogeneous mediums, on the general direction of the vibrating motioncommunicated.
Intensification of sounds. Interferences. Beats. Different stringed and wind instruments. Means of setting them in vibration.
A few words on the organs of voice and hearing. Incompleteness of our knowledge on this subject.
OPTICS.
Lessons 16–17.Propagation of Light.
Propagation of light in a straight line. Rays of light. Geometrical theory of shadows. Velocity of light. Rœmer’s observations. Laws of intensity of light. Photometers of Bouguer, Rumford. Intensity of oblique rays. Comparison of illuminating powers. Total brightness. Intrinsic brightness.
Reflection.
Reflection of light: its laws. Experimental demonstration. Images formed by one or more plane mirrors. To ascertain if a looking-glass has its two faces parallel.
Spherical mirrors. Foci, formulæ. Discussion. Images by reflection. Measure of the radius of a spherical mirror.
Definition of caustics by reflection. Definition of the two spherical aberrations in mirrors.
Woollaston’s goniometer.
Lesson 18.Refraction.
Refraction of light in homogeneous mediums. Descartes’ law. Experimental demonstration for solids and liquids.
Inverse return of the rays. Successive refractions. Indices of transmission in terms of the principal indices. Consequences of Descartes’ law. Total reflection. Manner of observing it.
Irregular refractions. Mirage.
Refraction is always accompanied with the accessory phenomenon of dispersion.
Geometrical consequences of the law of refraction. Focus of a plane surface. Focus of a medium bounded by two parallel plane surfaces; by two plane surfaces inclined in the form of a prism.
Foci of a spherical surface; of a medium limited by two spherical surfaces. Lenses.
Formula for lenses. Discussion. Varieties of lenses. Optic center. Images. Measure of the focal distance of lenses.
Definition of caustics by refraction. Definition of the two spherical aberrations of a lens.
Lessons 19–20.Dispersion.
Unequal refrangibility of the differently colored rays which compose white light. Analysis of heterogeneous light by the prisms. Newton’s method. Solar spectrum. Homogeneity of the different colors. Second refraction of a homogeneous pencil. Experiment with crossed prisms. Precautions to be attended to in the experiments. The spectrum, obtained by Newton’s method, differs from the spectrum produced at the focus of a lens placed between the prism and the picture, according to the method of Fraunhofer. Reasons of the comparative purity of this latter spectrum. Fraunhofer’s lines. Different spectra of different sources of heterogeneous light. Marginal iridescence of a large pencil of natural light traversing a prism. Dispersion of light by lenses. Iridescence of focal images. Recomposition of light, by means of a prism at the focus of a spherical mirror or a lens, by the rapid rotation of a plane mirror, by the rotation of a disk with party-colored sectors. Compound colors.
Chemical and calorific radiations accompany luminous radiations.
Analysis of light by absorption. Characteristic action of transparent colored mediums upon different sorts of compound light. Different influences of increasing thickness. Effects of differently colored mediums upon heterogeneous light. Effects of differently colored mediums upon homogeneous rays separated by the prism.
Lesson 21.Measure of the Indices of Refraction.
Determination of the indices of refraction.
1. In solids. Measure of the refracting angles. Minimum of deviation. Measure of the corresponding deviation. Use of Fraunhofer’s lines.
2. In liquids.
3. In gases. Special difficulties of the question. Experimental method. Biot’s and Arago’s experiments.
Any power whatever of the index of refraction diminished by unit is sensibly proportional to the density of the gas. Method of Dulong founded on this remark.
Lessons 22–23.Application of the preceding Laws.
Rainbow. Different orders of bow.
Achromatism.
Achromatic prisms. Diasperometer achromatism of lenses; how to verify it. Definition of secondary spectra: their nature gives the means of recognizing, whether flint or crown glass predominates, in an imperfectly achromatic lens.
Instruments essentially consisting of an achromatic lens. Magic lantern; megascope; solar microscope; camera obscura; collimators.
Vision.
Summary description of the principal optical parts of the eye. They act like the lens of a camera obscura to form an image upon the retina. Distinct vision; optometers; short sight; long sight; spectacles.
Binocular vision; perspective peculiar to each eye; estimation of distances; sensation of solidity; stereoscope; estimation of magnitudes.
PERSISTENCE OF IMPRESSIONS; DIVERS EXPERIMENTS.
Lessons 24–26.Optical Instruments.
Camera lucida.A lens is necessary to reduce to the same apparent distance the two objects seen simultaneously. Instruments to assist the sight; simple microscope; the magnifying power; distinctness; field; advantage of a diaphragm; it modifies the field and the brightness variously according to its position.
Woollaston’s double glass; its advantages.
General principle of compound dioptrical instruments.
Compound microscope; experimental measure of its magnifying power, by means of the diaphragm, by means of the camera lucida.
Astronomical telescope; object glass; simple eye-glass. Necessity for a diaphragm; its place; the wires, their place; optic axis of a telescope. Parallax of the threads of the wires; magnifying power of the object-glass; of the eye-glass; field of view of a telescope.
Optic ring; different methods of measuring the magnifying power.
Distinctness of a telescope; night-glass.
Different distances of drawing out the eye-glass for short-sighted and long-sighted observers.
Different sorts of eye-pieces; positive eye-pieces; ordinary double eye-piece of the astronomical telescope. Ramsden’s eye-piece; treble eye-piece of the terrestrial telescope. Negative eye-pieces; simple eye-piece of Galileo. Compounddittoof Huyghens; advantages and disadvantages of these different combinations; general principle of catadioptrical instruments.
Lessons 27–29.Double Refraction.
Crystallized mediums do not all act upon light like homogeneous mediums.
Double refraction of Iceland spar: the extraordinary image turns round the ordinary image. The ordinary and extraordinary rays cross at the interior of the crystal.
Huyghens’ construction; measure of the ordinary and extraordinary indices of refraction; attractive and repulsive crystals; a ray falling perpendicularly does not always bifurcate in a camera with parallel faces, nor in a prism. Definition of uniaxial and biaxial crystals.
The dispersion of the ordinary ray differs from that of the extraordinary ray.
The two rays are unequally absorbed in many colored mediums. Tourmaline.
Doubly-refracting prisms; their construction. Use of doubly-refracting prisms to measure apparent diameters, &c.
Lessons 30–31.Polarization.
Successive refractions in doubly-refracting prisms. Special properties of the two rays emerging from the first doubly refracting crystal. Polarization by double refraction.
Reflection from transparent media polarizes the light partially or wholly according to the incidence. Brewster’s law. Reflection of polarized light from a transparent medium.
Simple refraction partially polarizes the light. Many successive refractions polarize it almost totally. Piles of glasses.
Different methods to obtain a ray of polarized light, 1st, by reflection; 2nd, by simple refraction; 3rd, by double refraction, by eliminating one of the refracted pencils;—by a screen,—by total reflection, Nicol’s prism, by absoption, tourmaline.
Distinctive characters of light completely or partially polarized.
Lessons 32–34.Theory of Undulations.
Hypothesis of luminous undulations.
Vibratory state of a simple ray of homogeneous light. Vibratory state at the inter of two simple rays of homogeneous light intersecting at a very small angle.
Experimental proofs in support of this hypothesis:
1st. Experiment with interferences, fringes. Their breadth is different for different colors; they give the various colors of the prism in white light. The alternately bright and dark sheets are hyperboloids of revolution. The measure of the fringes give the means of estimating the lengths of the undulations corresponding to different colors.
2nd. Colored rings of Newton, observed by reflection, by refraction. Law of the diameters; these vary in absolute length for different colors. Variously colored rings with white light. Reflected rings with a white spot at the center.
The theory of the undulations does not apply merely to theses phenomena. Explication of the laws of reflection and refraction. Definition of polarization in the system of waves. Elementary application of double refraction and the polarization which accompanies it in uniaxial crystals when the face of the crystal is parallel to the axis, and the plane of incidence normal or parallel to this axis.
Chemical and Calorific Radiations.
Chemical and calorific radiations are subject, like luminous radiations, to the laws of reflection, refraction, dispersion, double refraction, polarization, interferences.
Lessons 35–36.Revision.
Considerations on the totality of the subjects of the course.
MANIPULATIONS IN PHYSICS.
The practical exercises which constitute the subject of this programme will be performed in part by the pupils under the direction of the professors andrépétiteurs, in part by the professors andrépétiteurs, with the coöperation of the pupils.
FIRST YEAR.
Use of various instruments, designed for measuring lengths. Experiments on weight with Atwood’s machine, the inclined plane, Morin’s apparatus, and the pendulum.
Some experiments on elasticity.
Various verifications of the principles of hydrostatics and hydrodynamics.
Construction of aerometers.
Construction of a barometer, of a manometer. Various verifications of the law of Mariotte.
Various experiments with the air-pump.
Determination the density of solids or liquids by different methods.
Construction of a thermometer.
Experiments on the dilatation of liquids and solids by means of the ordinary thermometer and by means of the statical thermometer.
Experiments upon the dilatation of air by various methods.
Experiments upon the tension of vapors by different methods.
Determination of the density of vapors and gases by various methods.
Leading experiments on calorific radiation.
Experiments on cooling.
Determination of specific heats, heats of fusion, heats at which bodies pass into vapor.
Cooling mixtures.
Use of the chemical hygrometer, the wet bulb hygrometer.
Rehearsal of the leading experiments on magnetism.
To magnetize a needle, to reverse its poles.
Rehearsal of the principal experiments of statical electricity.
Experiments verificatory of the laws of electricity and magnetism.
Use of compasses.
SECOND YEAR.
Experiments upon the chemical actions of poles.
Leading experiments in electro-dynamics.
Leading experiments upon the magnetic properties of currents.
Experiments on induction.
Experiments on the calorific and luminous actions of currents.
Quantitative experiments on the laws of currents.
Experiments on the propagation of sound; on the vibrations of rods of plane or curved plates, membranes, sonorous tubes.
Experiments on mirrors, plane or curved.
Experiments on lenses. Experiments on the decomposition of light by the prism—by absorption. Measures of the indices of the refraction of solids. Use of the magnifying glass and microscope; measure of the magnifying power. Use of different telescopes, with and without corrections. Measure of the magnifying power. Experiments on double refraction and polarization. Experiments on interferences and colored rings.