Carré and Co.'s freezing machine,

102.

Casella's minimum thermometer, 22.
Caus, S. de, conception of a steam
engine, 324.

Cawley's steam engine, 325.
Celsius, thermometric scale of, 13.
Centigrade thermometer, 13.
Chamber of constant temperature,
184.

Chemical affinity, effect of on vapo-

rization, 97; how affected by
temperature, 156; action of sun's
rays on, 168.
Chemical separation, a form of energy,
299; connection with heat, 339.
Chlorine, combustion in, 343.
Clausius on energy, 296; on motion
of gases, 367.

Clément and Désormes, 283.
Coal, potential energy of, 354; ex-
haustion of, 357.

Coefficient of dilatation, 25; in-

creases with temperature, 36.
Cold of freezing mixtures, 85; due
to vaporization, 101; apparent
reflection of, 182.

Colours, how related to wave-length
of rays, 162.

Combustion, energy derived from,
339, 354.

Comets, probably composed of in-
candescent gas, 221.
Compensation balance, 76.

Compound bodies, atomic heat of,
277.

Condensation, 118; instrument for,
119; of gases, 305.
Conduction of heat, 238.

Conductivity defined, 243.

Conductors, bad, of heat, 155, 239.
Contents, summary of, I.

Contraction from boiling-points, 51;
of metals, 78.

Convection of heat, 256.

Cooling, velocity of, 207, 260; me-
thod by, for measuring specific
heat, 266.

Cornish engines, 329.
Crawford, 340.

Crookes discovered thallium, 219.

Cryophorus, the, 101.
Crystals, dilatation of, 37; conduc-
tion of heat in, 254.
Crystallization, 92; anomalies in, 93.
Cubical dilatation, 32; method of
measuring, 32; table of, 34; re-
lation to linear, 35.

Cumming on thermo-electric inver-
sions, 153.

Currents, thermo-electric, 148; earth-,
358.

Dale and Gladstone on effect of

temperature on refraction, 147.
Dalton's investigations on expansion
of gases, 55; law of maximum
pressure, 96; on vapour tensions,
133; on combustion, 340.
Daniell's measurement of dilatation,

28; dew-point hygrometer, 141.
Dark heat, 167; reflected, 169; re-
produces optical phenomena, 179;
limit of, 215; absorption of, 222.
Davy, Sir H., first studied influence

of temperature on electricity, 154;
his safety-lamp, 253; on friction,
295; on combustion, 340; on
nature of flame, 344.

De la Rive and De Candolle on con-

ductivity of wood, 254.

De la Roche on absorption of heat,
175, 222; and Bérard on specific
heat of gases, 271.

De La Rue on the sun's red flames,
359.

Density, standards of, 70; effects of

temperature on, 0; change of,
in melting, 83; of vapours and
gases, 133; laws of, 134; of
steam, table of, 136.
Despretz, table of dilatations of
water, 49; on lowering of freez-
ing-point, 88; on density of gases,
134; on conductivity, 249; on
latent heat, 283; on combustion,
340.
Dew-point, 138; hygrometers, Da-

niell's, 141; Regnault's, 141.
Diathermanous, 175.
Differential thermometer, 22.
Diffuse reflection of heat, 173.

Digester, Papin's, 109.
Dilatation, application of laws of,
65; causes convection of heat,
258.
Dilatation of gases, 53; Boyle's law
of, 53; experiment on, 55; Gay
Lussac's law of, 55; relation be-
tween temperature and pressure of
air, 56; between temperature and
volume, 59; air thermometer, 61.
Dilatation of liquids, 39; apparent
and real, 39; methods of deter-
mining, 39; of mercury, 41; of
water, 47; of other liquids, 49;
of volatile liquids, 50; contraction
from boiling-points, 51.
Dilatation of solids, 24; experiment
shewing, 24; of uncrystallized
solids, 25; coefficient of, 25;
linear, 26; sources of error, 31;
cubical, 32; relation of cubical
to linear, 35; increases with tem-
perature, 36; of crystals, 37;
general remarks on, 37.

Dispersion, effects of temperature on,
147.

Dissipation of energy, 347.
Distillation, 100.

Dixon on heat, 131; his tables of
pressure of aqueous vapour, 369.
Donati, investigations into substance
of comets, 221.

Donny on boiling-point of pure
water, III.

Double-action of steam engines in-
vented by Watt, 328.

Drion's observations on volatile li-
quids, 51; laws of liquids in a
capillary tube, 157.

Drops, Prince Rupert's, 338.
Dry and wet bulb hygrometers, 142.
Dulong and Arago's experiments on

pressure of aqueous vapour, 123.
Dulong and Petit's observations on
cubical dilatation, 34; method of
measuring dilatation of liquids,
42; of gases, 55; experiments on
cooling in vacuo, 207; in a gas,
260; on specific heat, 267; on
atomic heat of bodies, 276.
Dumas on density of gases, 134.

Earth-currents, 358.
Ebullition, 108.

Elasticity, change of, in gases, 54;
of vapours and gases, 120.
Electric conductivity, how affected
by temperature, 154; similar to
thermal, 251.

Electrical separation a form of po-
tential energy, 299.
Electricity, effects of temperature on,
148-155; a form of molecular
energy, 298; how converted into
heat, 331.

Encke's comet, 353.
Energy, remarks on, 287; definition

of kinetic, 289; potential, 292;
problems in, 296; forms of, 297;
laws of transmutation of, 299;
connection between heat and me-
chanical energy, 301; connection
between heat and other forms of
energy, 331; dissipation of, 347;
article on, in North British Re-
view, 353; sources of, 354.
Engines, reversible, 310, 318; heat,
history of, 321.

English standard of length, 65; of
weight, 68; of density, 70.
Eolipyle of Hero, 322.

Equilibrium of heat rays, 184; of
light rays, 199.

Erman's observations on Rose's fusi-
ble metal, 37.

Errors in thermometers, 15, 16; how
corrected, 17.

Evaporation, cold of, 101; its laws,
107.

Exchanges, theory of, in heat, 181.
Expansion of metals, 78; practical
methods of allowing for, 79.
Expansive working of Watt's steam
engine, 328.

Eye,how affected by different rays, 215.

Fahrenheit's scale, graduation of, 13.
Fairbairn and Tate's experiments on
density of steam, 135.
Faraday on regelation, 89; on cold
from evaporation, 102; on Leiden-
frost's phenomenon, 114; on lique-
faction of gases, 117, 118.

Favre and Silbermann measure latent
heat of vapours, 285; on heat of
combustion, 340; tables of, 342.
Flame, nature of, 344.

Fluctuation thermometer, 23.
Fluids, conductivity of, 255.
Fluorescence, 234; likeness to phos-
phorescence, 236; practical uses
of, 237.
Fluxes, 85.

Food, potential energy of, 354.
Forbes, explanation of regelation, 89;
on refraction of dark heat, 174;
on absorption of heat, 176; on
polarization of heat, 177; on flow
of heat along a bar, 244; on va-
riation of conductivity with tem-
perature, 250; actinometric ob-
servations, 361.

Formulæ of interpolation, 126.
Foucault's experiments on light rays,

203; on revolving disk, 304.
Fourier on flow of heat across a wall,
240; along a bar, 244.
Frankland on tidal energy, 356.
Fraunhofer on solar spectrum, 175,

219.

Freezing mixtures, 85; of a lake,
87; apparatus, 101; Carré's ma-
chine, 102.
Freezing-point, 9; lowering of, 87;
under pressure, 362.

French standard of length, 67; of
weight, 69; of density, 70.
Friction, Joule's experiments on,
302.

Fuel, potential energy of, 354.
Fusion, 82; latent heat of, 83; of
ice, used as a method of measur-
ing specific heat, 265.

Galileo recognised the functions of a
machine, 293.

Galvanometer, Professor W. Thom-
son's, 150.

Gas, ordinary, heat of flame of, 344.
Gaseous motion, theory of, 368.
Gases, dilatation of, 53-61; con-

densation of, 118, 305; pressure
of, 120; density of, 133; radiation
of, 216; absorption by, 224;

convection in, 258; specific heat
of, 271; heat evolved from solu-
tion of, 345; energy of motion
of, 368.
Gassiot's investigations in electricity,
332.

Gay Lussac's table of contraction of
liquids, 51; law of dilatation, 55,
62; on the vapours from mixed
liquids, 97; observation on effect
of vessel on boiling-point, 110;
no effect produced on vapour ten-
sion by change from liquid to
solid state, 132; law of density
of gases, 133; method of research
on density of gases, 134.
Geysers of Iceland, convection of
heat in, 257.

Gladstone and Dale on effects of tem-

perature on refraction, 148.
Glass, radiation from, 191; light
rays from transparent, 200; from
coloured, 201.
Glauber's salt, 93.

Globe, with athermanous envelope,
228; the terrestrial, 230; unequal
temperature of, a source of energy,
357.

Graduation of mercurial thermo-
meter, 13; Fahrenheit's scale, 13;
Centigrade, 13; Reaumur, 14;
how reduced, 14.

Graham's mercurial pendulum, 74.
Graphic representation. 126.
Grassi on effect of temperature on

compressibility, 157.

Gravity, specific, of mercury, 71;
table of, 112; of air and gases,
138, 144; affects convection of
heat, 258.

Gridiron pendulum (Harrison's); 74.
Grove's experiments on boiling-

points, III; on energy, 297.

Haidinger on reflection from gold,
227.

Harrison's gridiron pendulum, 74.
Hartnup on temperature corrections
of chronometers, 76.
Haüy on electric properties of crys-
tals, 154.

Head of water, a form of potential
visible energy, 297, 354, 356.
Heat, definition of, I; measured by
thermometers, 7-24; causes dila-
tation of solids, 24-37; of liquids,
39-52; of gases, 53-61; effects of
on standards of length, weight, and
density, 65; on measures of time,
73; on barometric column, 77;
on expansion and contraction of
metals, 78; causes fusion, 82;
melting-points, 82, 84; latent, in
fusion, 83; effect on vaporization,
95; causes ebullition, 108; boiling-
points, 108-112; vaporization at
very high temperature, 116; effect
of on refraction and dispersion,
147; on electric properties of
bodies, 148; on magnetism, 155;
on chemical affinity, 156; on other
properties of matter, 156; radiant,
159; spectra of heated bodies,
166; reflection of, 169; refraction
of, 173; absorption of, 175; po-
larization of, 177; probable iden-
tity with light, 179; theory of
exchanges of, 181; heat rays,
equilibrium of, 184; for surfaces,
184; for thin plates, 191; inter-
nal radiation, 193; light rays,
equilibrium of, 198; radiation of,
at different temperatures, 205;
from lamp-black, 206; quantity
of, 207; quality of, 214; radia-
tion of, from a particle, 216; ab-
sorption of dark, 222; refrigera-
tion, 230; phosphorescence, 232;
fluorescence, 234; conduction of,
238; across a wall, 241; along a
bar, 244; conductivity of metals,
250; transmission of, compared
with transmission of temperature,
252; conduction in non-homo-
geneous solids, 254; in fluids, 255;
convection of, 256; in liquids,
256; in gases, 258; specific, 263;
measurement of, 264; of solids,
266; of liquids, 269; of gases,
271; atomic, 276; latent, 278;
of liquefaction, 279; of vaporiza-
tion, 283; is a kind of motion,

287; conversion of mechanical
energy into, 294; conversion of,
into mechanical energy, 296;
energy of radiant, 298; of ab-
sorbed, 298; laws of thermo-
dynamics, 301; caused by fluid
friction, 302; specific, of gases
of
constant volume, 307; engines,
theory of, 310; engines, history
of, 321; connection with electricity
in motion, 331; connection with
molecular potential energy, 336;
latent, 336; connection with
chemical separation, 339; units
of, developed in combustion, 342;
from metallic precipitates, 343;
absorbed when salts dissolve, 345;
evolved during solution of gases,
345; transmuted into energy of
chemical separation, 346; uni-
formly diffused, 351; of sun's
rays, 358; measure of tempera-
ture, 364.

Heat engines, 310; history of,

Jamin's experiments on effect of tem-
perature on refraction, 147; on
reflection of heat of light, 172.
Joule on specific heat of air, 271;
experiments in thermo-dynamics,
302; and on specific heat of gases,
308; investigation of heat of vol-
taic electricity, 334; on Peltier's
phenomenon, 335; on animal
energy, 355.

Kant on tidal energy, 356.
Kilogramme, the French standard of
weight, 69.

Kinetic energy, 289; energy of air
and water, 354.

Kirchhoff has developed Prevost's

theory, 184; experiments on light
rays, 203; researches into spectra,
219; discovery of presence of so-
dium, &c., in heavenly bodies,
219.

Knoblauch on reflection, 172.
Kopp's observations on cubical dila-
tation, 34;
on Rose's fusible
metal, 37; on contraction from
boiling-points, 52; on boiling-
points, 112.

Lambert on oblique radiation, 187.
Lamont's, Dr., experiment on eva-
poration, 105.
Lamp, safety, 253.

Lamp-black radiation, 185, 206; ve-
locity of cooling from lamp-black
surface, 214.