Conservation of energy, ii. 83, 431.
Constant numbers, i. 380; mathemati-
cal, 381; physical, 383; astronomical,
384; terrestrial, 385; organic, 385;
social, 386.

Continuity, sense of, ii. 117; detection
of, 262; law of, 268, 419; failure of,
273.

Continuous quantity, ii. 108.

Contrapositive propositions, i. 100, 101.
Conversion, i. 55; contrapositive, 97.
Copernican theory, i. 283; ii. 153, 281,
298, 310.
Copula, i. 19.

Corpuscular theory, ii. 150, 173, 304.
Correction, method of, i. 406.
Correlation, ii. 350, 354.

Cotes, Roger, means, i. 416; method
of least squares, 437; weighted ob-
servations, 450.

Couple, mechanical, ii. 318.
Creation, i. 170; ii. 416.

Crystallography, i. 153; ii. 162, 184,

311, 319, 359, 398, 450.
Crystals, pseudomorphic, ii. 324.

Curves, nature of, ii. 99; discovery of,

D'Alembert, probability, i. 244, 245;
gravity, ii. 81.

Dalton, laws of, ii. 82, 91, 274, 329.
Darwin, Charles, theory, ii. 8, 48, 165,
218, 405, 421; orchids, 19, 409;
classification, 410; reproduction, 421.
Davy, Sir H., instruments, i. 313; heat
of friction, i. 397; ii. 23; electro-
lysis, 29, 38.

Decandolle's system, ii. 387.
Deduction, i. 13, 59; probable, 239.
Definition, i. 64; ii. 397.

De la Rue, ii. 67, 109.
De Morgan, sign of equality, i. 18;
Aristotle's logic, 22; relatives, 27;
limited universe, 52; complex pro-
blems, 90; contrapositive conversion,
97; Euclid's indirect proof, 98;
logical problems, 116; error of sys-
tem, 135; numerically definite syllo-
gism, 190; probability, 226; experi-
ments on probability, 237; probable
argument, 239; trisection of angle,
268; finite experience, 300; arcual
unit, 358; personal error, 403; means,
419; average, 421 weighted obser-
vations, 450; works on probability,
459; apparent sequence, ii. 13; small
errors, 101; subequality, 102; gene-
ralisation, 249; catalogues, 403.

Density, unity of, i. 371; of earth, ii.

207; negative, 304.

Depth of oceans, i. 347.
Descartes, ii. 135, 290.
Development, logical, i. 104.
Diagnosis, ii. 394.
Diamond, ii. 159, 261.
Diatomaceæ, ii. 9, 410.

Difference, law of, i. 6, 87, 95; sign of,
20, 54; of numbers, 210: calculus of,
ii. 122; logical, 377.

Differential calculus, ii. 99; thermo-
meter, i. 400.

Diffraction of light, ii. 27.
Discontinuity, ii. 274.

Discoveries, accidental, ii. 162; pre-
dicted, 171.

Disjunctive terms, i. 79; conjunction,
80; proposition, 89, 127; syllogism,
92.

Donkin, i. 226, 227, 243, 248.
Double refraction, ii. 174, 231, 361.
Dove's law, ii. 168.

Draper's law, ii. 257.
Duality, law of, i. 87, 95.
Duration, i. 360.

E.

Eclipses, i. 343; ii. 322.

Electric acid, ii. 38.

Electricity, ii. 163, 187, 237, 264; unit
of, i. 379; theory of, ii. 154.
Electrolysis, ii. 37, 163.

Electro-magnetism, ii. 164.
Electrometer, i. 330.

Elements, classification of, ii. 347, 349,
364, 374.

Ellicott, on Clocks, ii. 70.
Ellipsis, logical, i. 69.
Elliptic variation, ii. 94.
Ellis, A. J., i. 27, 190, 194.
Ellis, W., effect of full moon,
Emanation, law of, ii. 82.
Emotions, ii. 424.

ii. 14.

Empirical knowledge, ii. 132, 157, 158;
measurements, 190.

Encke, Comet, i. 363; ii. 212; law of
error, i. 445; mean, 449; resisting
medium, ii. 155.

Energy, unit of, i. 376; conservation
of, ii. 83, 431.

Equality, i. 56, 183; sign of, 18;
meanings of, ii. 102.
Equations, i. 142, 180; ii. 51.
Equilibrium, unstable, i. 320; ii. 319.
Equivalence, logical, i. 132, 134; re-
markable case of, 162; ii. 323.
Eratosthenes, sieve, i. 96, 141, 160; on
latitude, 315, 342.

Error, function, i. 382; avoidance of,
393; personal, 402; rules for elimi-
nating, 409; law of, 434; formula of,

442; probable, 451; constant, 460;
theory of, ii. 90.

Ether, friction of, ii. 254.
Euclid, axioms, i. 183; incommensur-
ables, 319; right angle, 358; ana-
logy, ii. 289.

Euler, on knowledge, i. 273; gravity,
274; ii. 81; medium of light,
143; corpuscular theory, 152.
Exceptions, in induction, i. 152; classes
of, ii. 308; imaginary or false, 309;
apparent, 313; singular, 316; diver-
gent, 320; accidental, 324; novel,
328; limiting, 331; real, 336; un-
classed, 338.

Excluded middle, law of, i. 7.
Exclusive alternatives, i. 234.
Experiment, ii. 2, 22; simplification of,

30; failure in, 33; blind or test, i.
402; ii. 43; negative results of, 45;
limits of, 48; collective, 57; discord-
ance of, 198.

Experimentum crucis, ii. 135, 337.
Explanation, ii. 157, 166.

Extent of, logical terms, i. 31; propo-
sitions, 57,

Extrapolation, ii. 120.

F.

Factorials, i. 202.
Fallacies, i. 74, 117.

Faraday, Michael, on gold-leaf, i. 346;
gravity, 396; ii. 236; magnetism
of gases, i. 407; lycopodium, ii. 25;
electrolysis, 29, 32, 83; electric poles,
29; electro-magnetism, 31, 184, 274;
polarized light, 31, 318; precautions
in experiment, 40; lines of force, 58;
Arago's experiment, 170; velocity
of electricity, 180; his researches,
223; reservation of judgment, 240;
heavy glass, 261; electricity, 264;
radiant matter, 304; hydrogen, 366.
Fatality, i. 305.

Figurate numbers, i. 212, 214.
Figure of earth, ii. 76, 207.
Fizeau, Newton's rings, i. 347; ii. 227;

quartz, i. 367; revolving mirror, 349.
Flamsteed, i. 314; use of wells, 342;
standard stars, 351; parallax of pole
star, 391; choice of observations,
415; instruments, 456; solar eclipses,

ii. 109.
Fluorescence, ii. 332.

Forbes, J. D., i. 286; ii. 89, 454.
Force, unit of, i. 375.
Fossils, ii. 327.

Foucault, revolving mirror, i. 349;
pendulum, 396; ii. 41; velocity of
light, 53, 202.

Fourier, theory of heat, ii. 89, 438.

Fowler, Professor, inductive inference,
i. 261; method of variations, ii. 51.
Freezing mixtures, ii. 183.

Fresnel, inflexion of light, ii. 27; double
refraction, 59; undulatory theory,
173.

Friction, determination of, i. 401; heat
of, ii. 22, 187.

Functions, definition of, ii. 113; dis-
covery of, 121.

G.

Galileo, falling bodies, i. 333; differ-
ential method, 399; projectiles, ii.
85; gravity, 254; continuity, 270.
Galton, Francis, i. 214, 373; ii. 321.
Galvanometer, i. 407.

Gas, ii. 90, 250, 266, 320, 334.
Gauss, use of mirror,

334; pendulum
experiments, 370; ii. 81; law of
error, i. 436; constant errors, 461.
Gay-Lussac, barometer, i. 401; law of,
ii. 274; boiling point, 325.
Genealogical tree, ii. 407.

General names, twofold meaning of,
i. 31.

General principles, ii. 309; reasoning
by, 243.

Generalisation, ii. 242, 389; two mean-
ings of, 246; value of, 248; hasty,
278.

Genius, ii. 219, 321.

Genus, ii. 376; generalissimum, 379,
382; natural, 414.

Geology, ii. 327, 335, 337; negative
arguments in, 18.
Geometric mean, i. 418.

Geometry, reasoning in, i. 183, 268, 309.
Gilbert, Copernican system, i. 287;
magnetism, ii. 41; on experiment, 55.
Gold-assay process, ii. 45.
Gold-leaf, i. 346.

Gradation of character, ii. 410.
Graham, Professor, ii. 267, 366.
Grammar, rules of, i. 37; ii. 328;
equivalents in, i. 138.
Granite, classification of, ii. 422.
Graphical method, ii. 116.
Gravity, ii. 29, 75, 95, 96, 141, 144,
254, 313; measure of density, i. 371,
375; uniformity of, ii. 36, 56; Hooke's
experiments, 46; law of, 80; Fara-
day's experiments, 236.

Great Britain steamship, voyages of,
i. 453.

Grove, ii. 267, 268; magnetism, i. 397;
medium of light, ii. 143.

H.

Halley's Comet, ii. 172, 315.

Hamilton, Sir William, on reasoning,

i. 136; free will, 257; quantification

of predicate, ii. 387.
Hamilton, Sir W. Rowan, ii. 175.
Haughton, Rev. S., on muscular exer-
tion, ii. 114.

Heat, ii. 297; unit of, i. 378; measure-
ment of, 405; mechanical equivalent
of, ii. 211.

Heavy glass, ii. 235, 260.

Helmholtz, sound vibrations, ii. 8, 20,
98.

Hereditary descent, ii. 407.

Herschel, Sir J. F. W., plagihedral
quartz crystals, i. 148, 283; density
of earth, 210; photometry, 316,
352; numerical precision, 317; unit
of length, 367; actinometer, 389;
use of mean, 421; method of least
squares, 437; double stars, 457; ii.
125; active and passive observation,
2; fluorescence, 2; full moon, 15;
comets, 16; spectrum, 39; collective
instances, 59; principle of forced
vibrations, 65, 332; meteorological
variations, 112; direct action, 129;
use of theories, 136; ethereal
medium, 145; experimentum crucis,
149; interference of light, 175;
interference of sound, 176; residual
phenomena, 212; discovery by ana-
logy, 286.

Hindenburg, combinatorial analysis, i.
198.

Hipparchus, i. 337; ii. 306; use of
i. 342.

moon,

Hobbes, cause, i. 257; time, 359;
hypothesis, ii. 138.

Hofmann, crith, i. 374; prediction, ii.

181; anomalous vapour densities, 340.
Homogeneity, law of, i. 179.
Hooke, ii. 153, 342; gravity, 46;
philosophical method, 135; memory,
288.

Horrocks, use of means, i. 415; hypo-

thesis, ii. 135; planetary motions,

281.

Huxley, on classification, ii. 348, 354.
Huyghens, Saturn's satellites, i. 341;

ii. 280; pendulum, i. 353, 369;
cycloidal pendulum, 394; differential
method, 399; stars, ii. 8; projectiles,
85; philosophical method, 135; un-
dulatory theory, 151; double refrac-
tion, 231; analogy, 301.
Hybrids, ii. 416, 417.
Hydrogen, dilatation of, ii. 91; refrac-
tive power, 160; metallic nature of,
366.

Hygrometry, ii. 206.

Hypothesis, use of, i. 262; requisites
of, 307; substitution of simple, ii.
74; representative, 156; descriptive,
359.

I.

Identity, expression of, i. 18; pro-
pagating power, 24; simple, 44;
partial, 47; limited, 51; inference
from, 61, 66.

Illicit process, i. 77, 119.
Incommensurables, i. 319.
Independence, of events, i. 233; of
small effects, ii. 96.

Indexes, value of, ii. 405.
India-rubber, ii. 182.

Indifferent circumstances, abstraction
of, i. 112; exclusion of, ii. 26.
Indirect method, i. 133; ii. 370; rules
of, i. 105; illustrations of, 113.
Induction, i. 13, 70, 139; inverse
nature of, 14; of partial identities,
149; perfect, 164; imperfect, 168;
grounds of, 262.

Inequality, reasoning by, i. 184, 186.
Inference, process of, i. II; immediate,
60; from two simple identities, 61;
sum of predicates, 73; with disjunc-
tive propositions, 90; indirect method
of, 95; nature of, 136; mathe-
matical, 183.

Infima species, ii. 380, 382.
Infiniteness of universe, ii. 431.
Inhabitants of planets, ii. 301.
Instantiae, citantes, evocantes, radii,
curriculi, i. 313; monodicae, irregu;
lares, heteroclitae, ii. 260; clan-
destinae, 262.

Insufficient enumeration, i. 199.
Insulators, ii. 265.

Intension, of logical terms, i. 31; pro-
positions, 57.

Interpolation, ii. 120.

Inverse, operation, i. 140; problem,
154.
Iodine, ii. 155, 366.

Iron, magnetic power of, ii. 40.
Isomorphism, ii. 312, 330.

J.

Jet of water, ii. 9, 58, 60.
Jevons, W. S., cirrous clouds, ii. 15;
elevated rain-guage, 40; experiments
on liquids, 60; experiments on
muscular exertion, 114; cometary
retardation, 213; microscopic move-
ments, 264.

Joule, ii. 179, 182, 187, 197; thermo-
pile, i. 349; heat of compression,
350; temperature of air, 398; ex-
periments on heat, 402; measure-
ment of temperature, ii. 47; gases,
56; equivalent of heat, 211.
Jupiter, satellites of, ii. 298, 322;
eclipses of satellites, i. 433; figure
of, ii. 196.

Lagrange, formula for interpolation, ii.
123; character of, 282; on algebraic
geometry, 291.
Language, ii. 284, 305.
Laplace, probability, i. 227, 247; rule
of inverse method, 279; planetary
movements, 288, 289; solution of
inverse problem, 296, 311; long
inequality of Jupiter and Saturn,
342; atmospheric tides, 426; obser-
vation of tides, 432; law of error,
438; works on probability, 460;
dark stars, ii. 7; hyperbolic comets,
II; knowledge, 13; velocity of
gravity, 45; stability of planetary
system, 61, 441; phases of Venus,
63; corpuscular theory, 152; figure
of Jupiter, 196; figure of earth,
207; velocity of sound, 214; chemical
affinity, 268; laws of force, 392;
on Universe, 431.

Latent heat of steam, ii. 80.
Lavoisier, oxygen, i. 274; ii. 336;
decomposition of water, 3; simplifi-
cation of experiments, 31; definition
of element, 36.

Law, of identity, difference, duality,
excluded middle, of thought, &c., i.
6, 7, 87, 88, 95; of things, 8;
disjunctive relation, 85; commuta-
tiveness, 85, 180, 200; Bode's, 165,
297; homogeneity, 179; error, 434;
exact, ii. 79; discovery of, 90;
Dalton's, 82, 91, 274, 329; empirical
mathematical, 110; empirical quan-
titative, 125; of emanation, 82; of
nature, 143; Dove's, 168; Draper's
257; Carnot's, 257; of continuity,
268, 419; of motion, 270; reign of,
428; natural, 429.

Least squares, method of, i. 437, 458.
Legendre, geometry, i. 319; least

Lindsay, T. M., i. 26.

Linnæus, ii. 399, 415, 416.
Liquids, ii. 251, 267, 320, 334.

Locke, on number, i. 176; probability,
246; power, 254.

Logarithms, errors in tables of, i. 278;
calculation of, iì. 6.

Logical Abecedarium, i. 107, 109, 214,
234; ii. 367, 380, 387; abacus, i.
119; slate, 110; machine, 123.
Lucretius, atoms, i. 256; ii. 435; in-
destructibility of matter, 277; gravity,

313.

M.

Machine, logical, i. 123; Smee's, 124.
Macleay's system, ii. 407.
Magnetism, and light, ii. 234; attrac-
tion of, 256; universality of, 274;
animal, 342.

Mallet, on earthquakes, i. 368.
Malus, polarization of light, ii. 163.
Mammalia, ii. 354, 372.
Mansel, i. 83; ii. 384.

Mariotte, law of, ii. 91, 274.
Mars, poles of, ii. 245, 300.
Maskelyne, personal error, i. 402; den-
sity of earth, ii. 209.
Mass, unit of, i. 372.
Materialism, ii. 428.

Mathematics, reasoning in, i. 173, 270;
empirical discovery in, 266; nega-
tive inductive arguments in, ii. 20;
incompleteness of, 451.
Maxwell, Clerk, on Balances, i. 355;
speed of electricity, ii. 54; on Fara-
day, 224.

Mean, method of, i. 414; derivation
of word, 418; fictitious, 422; precise,
424; probable, 447.
Measurement, exact, i. 313; conditions
of accurate, 328; instruments of, 330;
by natural coincidence, 341; modes
of indirect, 345; systematic perform-
ance of, 351; attainable accuracy,
354 units and standards of, 357;
explained results of, ii. 193; accord-
ance of, 201; best mode of, 204;
agreement of distinct modes, 206.
Melvill, Thomas, ii. 38.
Metals, i. 298; ii. 365.

Meteorology, interpolation in, ii. 122 ;
results in, 191.

Meteors, observation of, i. 432; ii. 16;
number of, 12.

Method, inverse, i. 279; of measure-
ment, 332; repetition, 335; indirect
measurement, 345; of avoidance of
error, 393; differential, 398; correc-
tion, 400; compensation, 406; re-
versal, 410; means, 416; least squares,
437; ii. 116; variations, ii. 50; graphi-
cal, 116.

Metre, error in, i. 368; standard, 404.
Michell, on probabilities, i. 242; star-
systems, 285; star-discs, 455; torsion
balance, ii. 208; Pleiades, 299.
Milky Way, ii. 299.

Mill, J. S., on exclusive alternatives, i.
83; probability, 227, 245; cause,
254; inductive inference, 261; ii.
242; deductive method, i. 307; ii.
136; erroneous remarks on mean, i.
448; joint method of agreement, &c.,
ii. 34; method of concomitant varia-
tions, 106; collocations, 434.
Mineralogy, classification in, ii. 349,
406.

Momentum, unit of, i. 375.

Moon, fallacy concerning, ii. 14; atmo-
sphere of, 45; periods of, 63; motions
of, 107.

Muscular, susurrus, i. 348; exertion, ii.
114.

N.

Negative terms, i. 17, 88; premises,
75; arguments, ii. 16, 276; results
of experiment, 45.

Newton, Sir Isaac, binomial theorem,
i. 266; planetary movements, 288;
intervals of octave, 303; velocity of
sound, 344; ii. 87, 214; measure-
ment of light waves, i. 346; tides,
347; pendulum experiments, 354;
ii. 55, 254; absolute time, i. 360;
impact, 403; experiments on spec-
trum, ii. 25, 28, 32; Newton's rings,
27, 59, 60, 89; inflexion of light, 27;
gravity, 29; achromatic lenses, 42;
resisting ether, 46; absorption of
light, 58; theory of planetary motions,
73, 84, 86; resisting media, 86;
differential calculus, 99; alchemy,
133; knowledge of Bacon's works,
134; on hypotheses, 144; natural
colours, 147; vortices, 147; corpus-
cular theory, 151; fits of easy re-
flection, &c., 154; combustible sub-
stances, 159; discovery of gravitation,
194; rules of philosophizing, 258,
280; undulatory theory, 295; nega-
tive density, 304.
Newtonian method, ii. 226.
Noble's chronoscope, i. 360; ii. 270.
Nomenclature, ii. 418.

Numbers, prime, 141; of Bernouilli,
143; nature of, 175; concrete and
abstract, 178; triangular, 209; figu-

rate, 212.

Numerically definite reasoning, i. 190.

0.

Observation, ii. I; distinction from ex-
periment, 2; mental conditions of, 4;

instrumental and sensual conditions
of, 7; external conditions of, 10;
weighted observations, i. 449.
Odours, ii. 424.

Oersted, ii. 164, 169, 184.

Order, of terms, i. 40; of premises, 131.
Oscillation, centre of, i. 423.

Ostensive instances, ii. 259.
Ozone, ii. 331.

P.

Parabola, ii. 74; orders of, 95; approxi-
mate, 122.

Parallax of sun, ii. 203.
Parallel forces, i. 422; ii. 317.
Paralogism, i. 75, 118.
Parity of reasoning, i. 310.

Partial identities, i. 47; inference from,
64, 66, 70, 71; induction of, 149.
Particular reasoning, ii. 242.
Pascal, arithmetical machine, i. 123;
arithmetical triangle, 206, 211; prob-
ability, 244, 246; barometer, ii. 149.
Passive state of steel, ii. 326.
Peculiar property, ii. 377.
Peirce, i. 27.

Pendulum, i. 339, 352, 369, 423; ii.
79, 254.

Perfect induction, i. 164.
Perigon, i. 358.

Permutations, of verses, i. 197; alpha-
bet, 203; cards, 277.
Perpetual motion, i. 256; ii. 277.
Personal error, i. 402.
Physical astronomy, ii. 76.
Plagihedral crystals, ii. 287.
Planets, conjunctions of, i. 205, 212;
ii. 322; coincidences concerning, i.
304; ii. 356.

Plateau's experiments, ii. 36.
Plattes, Gabriel, on divining rod, ii.
45; gradual effects, 49.

Plumbline, divergence of, i. 429.
Poisson, on probability, i. 280; sidereal
day, 362; works of, 460; Newton's
rings, ii. 89; inflexion of light, 174;
crystals, 180.

Polarized light, ii. 163, 234, 287, 296,
318.

Pole, of magnet, i. 424; of battery, ii.
29.

Pole-star, use of, i. 425; errors of
observation of, 446; singularity of,

ii. 317.

Porphyry, Isagoge, ii. 376; tree of, 381.
Port Royal Logic, i. 26.

Pouillet's Pyrheliometer, i. 390.
Powell, Baden, ii. 278, 327.
Predicables, ii. 375.

Prediction, ii. 157, 171; in science of
light, 173; in theory of undulations,
176; in other sciences, 178; by
inversion of cause and effect, 181.