INDEX. 



473 



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. loo, lot. 



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, Eoger, means, i. 416 ; method 

 of least squares, 43 7 ; weighted ob- 

 servations, 450. 



Couple, mechanical, ii. 318. 



Creation, i. 170 ; ii. 416. 



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



3",3i9. 359. 398. 45- 

 Crystals, pseudomorphic, ii. 324. 

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



115- 



Cuvier, i. 355 ; ii. 31. 

 Cyanite, ii. 261. 

 Cycloid, ii. 291. 



D. 



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, SirH., 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. 



Diatomacese, 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, ii. 14. 



Emanation, law of, ii. 82. 



Emotions, ii. 424. 



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, 



