CHAPTER VI. THE PENDULUM.

Construction of pendulum.-Simple pendulum.-Amplitude.-Period.-Formula for period.

-Isochronism.-Discovered by Galileo.-Period independent of material.-Length of

pendulum.-Equivalent simple pendulum.-Convertibility of axes of suspension and

oscillation. Kater's pendulum.-Determination of g.-Expression for g in terms of

latitude.--Centrifugal force.--Centripetal acceleration.-Experiments in illustration.—

Oblateness of the earth.-Effect of earth's rotation on gravity.-Universal gravitation.

-Determination of earth's mean density.-Variation of gravity with height.-Simple

vibrations.—Acceleration proportional to displacement.-Projection of uniform circular

motion.-Proof that simple vibrations are isochronous.-Proof of formula for period.-

Application to pendulum.-Reason of isochronism.-Cycloidal pendulum.-Centre of

mass.--Movements of translation and rotation produced by force applied to a free body.

-Motion of centre of mass never altered by mutual actions.-Moment of inertia.-

Angular momentum. - Energy of rotation. -Fly-wheel.-Centre of percussion.—

Momentum.-Kinetic energy.-Potential energy.-Work done equal to amount of

potential energy transformed into kinetic energy.-Effect of friction.—Conservation

of energy,

CHAPTER VII. THE BALANCE.

pp. 56-79.

Description of balance.-Its correctness defined and tested.-Double weighing.-Sensibility,

on what dependent.-Stability, instability, and indifference.-Bare stability secured

by weighing with constant load.-Knife-edge suspensions.-Specimen of delicate

balance.-Density and specific gravity.-Specific gravity flasks for solids and liquids.

-Table of specific gravities, with memoranda connecting specific gravities and den-

sities,

CHAPTER VIII. HYDROSTATICS.

pp. 80-89.

Transmission of pressure in fluids.-Fluid pressure always normal.-Pascal's principle.-

Principle of hydraulic press.-Pressure the same at the same depth.-Increase of pres-

sure with depth.-Free surface horizontal.-Surface of liquid in rotating vessel.-

Pressure on the bottoms of vessels.-Pascal's vases.-Experiment on upward pressure.

-Total and resultant pressure.-Hydrostatic paradox.-Backward movement of vessel

produced by discharge.-Hydraulic tourniquet and Barker's mill.-Centre of pressure.

-Total pressure depends on depth of centre of gravity,

pp. 90-103.

CHAPTER IX. PRINCIPLE OF ARCHIMEDES.

Resultant pressure on immersed body.-Equal to weight of displaced liquid.-Constitutes

loss of apparent weight.-Centre of buoyancy.-Experimental demonstration of prin-

ciple of Archimedes.-Body heavier or lighter than liquid.-Egg in fresh and salt

water.-Cartesian diver.-Conditions of stability of floating bodies.-Metacentre.-Use

of ballast.-Apparent exception to principle of Archimedes in case of small bodies.—

Floating needles.-No real exception.-Arrangement of liquids which do not mix.-

Phial of the four elements,
pp. 104-112.

CHAPTER X. APPLICATION OF THE PRINCIPLE OF ARCHIMEDES TO

THE DETERMINATION OF SPECIFIC GRAVITIES.

Weighing in air and water.-Weighing in air, water, and the given liquid.-Hydrometers.

-Two classes distinguished.-Hydrometers of constant immersion.-Nicholson's.—

Fahrenheit's.-Hydrometers of variable immersion.-Investigation of general formulæ.

—Beaumé's and Twaddell's hydrometers.-Alcoholimeter.-Specific gravities of mix-

tures.-Graphical method of interpolating degrees,

pp. 113-121.

CHAPTER XI. VESSELS IN COMMUNICATION. CAPILLARITY.

Liquids find the same level in communicating vessels.-Water-level.-Levelling between

distant stations.-Spirit-level.-Level with attached telescope.-Determination of

values of divisions on spirit-level.-Heights of different liquids in communicating

vessels.-Capillarity.-Surface of a liquid not horizontal near sides of vessel.—Capillary

elevation and depression in fine tubes.-Circumstances which determine capillary eleva-

tion and depression.-Law of diameters.-Modified by form of surface.-Principles

which govern capillary phenomena.-Definite angle of contact.-Definite surface-ten-

sion.-Application to tubes and parallel plates.--Normal pressure exerted by cylindrical

film.-By any curved film.-Film of soapy water.-Soap-bubble.-Plateau's experi-

ments.-Pressures at different depths when surface is concave or convex.-Apparent

attractions and repulsions of floating bodies.-Interior pressure due to surface action

when surface is plane.-Phenomena illustrative of differential surface-tensions.-Table

of surface-tensions.-Endosmose.-Crystalloids and colloids,
pp. 122-139.

CHAPTER XII. THE BAROMETER.

Weight of air.-Experiments of Aristotle, Galileo, and Otto Guericke.-Weight of a litre

of air at 760 mm. -Correction for gravity.-Atmospheric pressure.-Torricellian experi-

ment.-Pressure of a standard atmosphere.-Rising of water in pumps.-Pascal's ex-

periment at the Puy-de-Dôme.-Barometer in its simplest form.-Cathetometer.-

Fortin's barometer.-Vernier.-Ivory point adjustment.-Float adjustment.-Correc-

tion for temperature.-For capillarity.-For capacity.-Compensated scale.-Index

errors.-Errors and corrections have opposite signs.-Reduction to sea-level.-Reduc-

tion of barometric pressure to absolute measure.-Siphon barometer.—Wheel barometer.

-Marine barometer.—Board of Trade barometer.-Sympiesometer.-Aneroid.-Coun-

terpoised barometer.-Fahrenheit's multiple-tube barometer.-Photographic registra-

tion, .
pp. 140-161.

CHAPTER XIII. VARIATIONS OF THE BAROMETER.

Measurement of heights by barometer.-Height of homogeneous atmosphere.-Proof that

pressure decreases in geometric progression.-Investigation of hypsometric formula.-

Diurnal oscillation of barometer.-Irregular variations.-Their connection with weather.

-Inverse changes of barometer and thermometer.-Isobaric lines and synoptic charts.

-Barometric gradient.-Buys Ballot's law. -Storm-warnings,

CHAPTER XIV. BOYLE'S LAW.

pp. 162-169.

Statement of the law.-Mariotte's tube.-Despretz showed that different gases were un-
equally compressible.-Pouillet's apparatus.-Experiments of Dulong and Arago.
Regnault's experiments and results.-Manometers or pressure-gauges.-Open mercurial.
-Multiple-branch.-Compressed-air manometer.-Its graduation.-Tapering-tube.-

Bourdon's metallic gauge.-Pressure of mixed gases.-Absorption of gases by liquids

and solids.- Coefficient of absorption.-Adherent film of air,

CHAPTER XV. AIR-PUMP.

།

pp. 170-183.

Action of air-pump.-Calculation of exhaustion. Mercurial gauge.-Cocks.--Double-

barrelled pump.-Double action with single barrel.-Bianchi's pump.-Burst bladder.

-Magdeburg hemispheres.--Fountain in vacuo.— -Limits of exhaustion.-Leakage.-

Untraversed space. -Air in oil.-Mercurial air-pumps.-Kravogl's.-

Sprengel's.-Babinet's doubly-exhausting pump.-Deleuil's pump with free piston.-

Compression-pump.-Calculation of compression.—Applications of compressed air.--

Mont Cénis tunnel.-Caissons.-Pneumatic despatch.-Mining machines, pp. 184-207.

B

CHAPTER XVI. UPWARD PRESSURE OF THE AIR.

Baroscope.--Soap-bubbles with hydrogen.-Balloons.-Calculation of lifting power.—

Construction of balloons.-Parachute.-Lifting power nearly the same at different

heights when inflation is partial.-Limiting height.-Correction for weighing in

air,

CHAPTER XVII. PUMPS FOR LIQUIDS.

pp. 208-214.

Principle of suction.-Action of suction-pump.-Limiting heights.-Lift-pumps.-Force

necessary to raise piston.-Efficiency.-Mechanical arrangements for driving.-Forcing-

pump.-Plunger.—Fire-engine.-Double-acting pumps.-Rotatory pumps.—Hydraulic

press.-Bramah's cup-leathers,

CHAPTER XVIII. EFFLUX OF LIQUIDS.

pp. 215-225.

Torricelli's theorem.-Torricelli's formula for velocity of efflux.-Apparatus for experi-

mental verification.-Proof that velocity varies as square root of head.-Quantity of

liquid discharged.-Contracted vein.-Efflux tubes.-Flow through long pipes.-

Fountains.-Efflux from vessel containing confined air.-Pipette.-Magic funnel.—

Inexhaustible bottle.—Intermittent fountain.-Siphon.-Velocity of flow through

siphon.-Starting the siphon.-Siphon for sulphuric acid.-Vase of Tantalus.-Inter-

mittent springs.-Marriotte's bottle for constant flow,

pp. 226-239.

HEAT.

CHAPTER XIX. THERMOMETRY.

Heat.-Cold.-Temperature.-Expansion produced by heat.-Choice of thermometric

substance.-Construction of mercurial thermometer.-Fixed points.-Thermometric

scales.-Change of zero.-Value of a degree.-Sensibility.-Weight thermometer.-

Alcohol thermometer.—Self-registering thermometers.—Six's. — Rutherford's.

Phillips'.-Negretti's.-Walferdin's.-Sea and well thermometers.-Protection against

pressure of water.-Thermograph.-Metallic thermometers.-Secchi's meteorograph.

—Pyrometers.—Differential thermometers,

pp. 241-263

CHAPTER XX. FORMULE RELATING TO EXPANSION.

Expansion.-Expansion factor.-Coefficient of expansion.-Cubic, linear, and superficial

expansion.-Comparison of volumes and densities at different temperatures.-Correc-

tion of specific gravity for temperature.-Gases,

CHAPTER XXI. EXPANSION OF SOLIDS.

pp. 264-268.

Experiments of Laplace and Lavoisier.-Method of Ramsden and Roy.-Compensated

pendulums.-Force of expansion of solids,
pp. 269-274.

CHAPTER XXII. EXPANSION OF LIQUIDS.

Relation between apparent and absolute expansion.-Expansion of glass.—Expansion of

any liquid.-Maximum density of water.-Saline solutions.-Absolute expansion of

mercury.-Expansion of iron and platinum.-Convection of heat in liquids.-Heating

buildings by hot water.-Oceanic currents,

pp. 275-286.

CONTENTS.

CHAPTER XXIII. EXPANSION OF GASES.

xiii

Gay-Lussac's experiments.-Regnault's experiments.-Air-thermometer.—Absolute tem-

perature and absolute zero.-Regnault's pyrometer.-Density of gases, absolute and

relative.-Experimental determination.-Weight of a litre of air.-Table of densities

of gases. Draught of chimneys.-Stoves and fire-places,

CHAPTER XXIV. FUSION AND SOLIDIFICATION.

pp. 287-301.

Fusion.-Table of melting-points.-Latent heat.-Heat of fusion of ice.-Solution.—

Freezing mixtures.-Congelation.-Difficulty of making a commencement.-Cooling

of water to -20° C.-Crystallization.-Ice-flowers.-Supersaturation and sudden con-

gelation.-Change of volume in congelation.-Expansive force of freezing water.-

Melting-point raised or lowered by hydrostatic pressure.-Effect of stress in solids

upon melting and solution.-Regelation.-Apparent plasticity of ice.-Motion of

glaciers,
pp. 302-316.

CHAPTER XXV. EVAPORATION AND CONDENSATION.

Spontaneous evaporation.-Vapours and permanent gases.-Vapours at maximum density

and tension, or saturated vapours.-Maximum density and tension depend on tempera-

ture.-Effect of presence of gas or of another vapour.-Dalton's two laws.-Liquefac-

tion of gases.-Faraday's first method.-Thilorier's apparatus.-Bianchi's-Faraday's

later method.- Continuous transition from gas to liquid or from liquid to gas.-Experi-

ments of Cagniard de la Tour, Drion, and Andrews.-Critical temperature.-Latent

heat of evaporation.-Cooling by evaporation.-Causing water to freeze. And mer-

cury.-Carré's two forms of apparatus for making ice.-Cryophorus.-Solidification of

gases,

pp. 317-333.

CHAPTER XXVI. EBULLITION.

Phenomena of ebullition.-Definite temperature.-Constancy of temperature.-Tension of

vapour.-Theory of ebullition.-Effect of pressure on boiling-point.-Franklin's experi-

ment.-Determination of heights by boiling-point.-Hypsometer.-Papin's digester.—

Safety-valve.-Boiling-point of saline solutions.-Temperature of vapour evolved.—

Boiling-point of mixtures.-Difficulty of making a beginning without air.-Experi-

ments of Donny and Dufour.-Spheroidal state.-Freezing of mercury in red-hot

crucible.-Cause of the spheroidal state.-Distillation.-Conditions of rapid evapora-

pp. 334-348.

tion,

CHAPTER XXVII. MEASUREMENT OF TENSION AND

DENSITY OF VAPOURS.

Importance in connection with steam-engine.-Dalton's experiments on maximum tensions

of aqueous vapour.-Regnault's two methods of experiment.-Table of results.--

Representation by curve and empirical formulæ.-Vapours of other liquids. Expres-

sion of tensions in absolute measure.-Laws of combination by volume.-Relation of

vapour densities (not maximum) to chemical equivalents.-Meaning of "vapour-

density” of a substance.-Dumas' method of determining vapour-densities.—Example.

-Table of vapour-densities.-Limiting values as temperature increases.-Gay-Lussac's

method.-Volume of a given weight of steam,
pp. 349-363.

CHAPTER XXVIII. HYGROMETRY.

Technical meaning of "humidity."--Dew-point. -Hygroscopes.-Hygrometers. — De

Saussure's. - Dew-point instruments. - Leroy's. - Daniell's. - Regnault's. -Wet and

dry bulb.-Glaisher's factors.-Apjohn's formula, and discussion of the basis on which

it rests.—Chemical hygrometer.-Weight of given volume of moist air.—Volume of

saturated air.—Aqueous meteors.-Cloud and mist.-Supposed vesicles.-Howard's

nomenclature of clouds.-Causes of formation of cloud.-Rain.-Rain-gauge.-Annual

rain-fall.-Snow and hail.-Snow-crystals,

CHAPTER XXIX. RADIANT HEAT.

pp. 364-384.

Radiation.-Characteristics of.-Newton's law of cooling.-Dulong and Petit's law of

cooling.-Law of inverse squares.-Experimental proof.-Laws of reflection.-Burning-

mirrors.-Conjugate mirrors.--Reflecting, diffusive, absorbing, and transmissive powers.

-Coefficients of emission and absorption equal.-Absolute value of coefficient of

radiation for lamp-black.-Different kinds of heat-ray.-Theory of exchanges.-Ther-

mopile.-Experimental comparison of emissive powers.—And of absorbing powers.—

Tables of results.-Variation of absorption with source of heat.-Determination of re-

flecting powers. And diffusive powers.-Diathermancy.-Experimental measurement.

-Table of heat transmitted by different substances.-Diathermancy and transparency.

---Iodine in sulphide of carbon.--Rock-salt.-Diathermancy of gases.-Remarkable effect

of scents and of aqueous vapour.-Influence of thickness of plate upon amount of

absorption.-Connection between radiant heat and light.-Fluorescence and calor-

escence.--Selective emission and absorption.-Their equality.-Proof from reversal of

bright lines in spectrum.-Dew,

CHAPTER XXX. CONDUCTION OF HEAT.

pp. 385-413.

Conduction described and distinguished from radiation.-—Variable stage and permanent

state.--Influence of specific heat.-Definition of conductivity.-Mathematical note on

conduction during variable stage.-Experiments to illustrate differences of conductivity.

-Ingenhousz's apparatus.-Metals the best conductors.-Wire-gauze and Davy lamp.

-Domestic applications.-Experimental determination of conductivity.-Table of

results obtained by Wiedemann and Franz.-Forbes' determination of absolute con-

ductivity of iron.-Absolute conductivity of rock deduced from underground tempera-

tures.-Conduction in liquids.-Despretz's experiment on water.-Professor Guthrie on

conducting power of water.-Small conducting power of gases.-Accounts for warmth

of cloth, &c.—Norwegian cooking-box.-Conductivity of hydrogen,

CHAPTER XXXI. CALORIMETRY.

pp. 414-425,

Test of equal quantity.-Units of heat, gramme-degree, pound-degree, &c.-Thermal
capacity, or water equivalent.-Specific heat, or capacity per unit mass.-Capacity per
unit volume.-Experiment to illustrate differences of specific heat.-Measurement of
specific heat by fusion of ice.-Method of mixtures.-Note on temperature of mixtures.
-Calculation of experiment, with corrections.-Regnault's apparatus.-Table of specific
heats. Great specific heat of water.-Effect on climate.-Dulong and Petit's law.—
Equal thermal capacities of all atoms.-Specific heat of gases, at constant pressure, and
at constant temperature. Their laws.-Specific heat of air.-Ratio of the two specific
heats.-Changes of volume, pressure, and temperature when no heat enters or escapes.--
Latent heat of fusion.-Table of latent heats, and of specific heats in the two states.—
Latent heat of evaporation.-Despretz's apparatus.-Regnault's experiments.—Tables