INDEX. 



775 



Decypliering, 124. 



Deduction, 11, 49. 



Deductive reasoning, 534 ; miscel- 

 laneous forms of, 60 ; probable, 

 209. 



Definition, 39, 62, 711, 723 ; pur- 

 pose of, 54 ; of cause and power, 

 224. 



De Morgan, Augustus, negative 

 terms, 14 ; Aristotle's logic, 18 ; 

 relatives, 23 ; logical universe, 

 43 ; complex propositions, 75 ; 

 contraposition, 83 ; formal logic 

 quoted, 101 ; error of his system, 

 117 ; anagram of his name, 128 ; 

 numerically definite reasoning, 

 168-172 ; probability, 198 ; belief, 

 199 ; experiments in probability, 

 207 ; probable deductive argu- 

 ments, 209-210 ; trisection of 

 angle, 233 ; probability of infer- 

 ence. 259 ; arcual unit, 306 ; 

 mathematical tables, 331 ; per- 

 sonal error, 348 ; average, 363 ; 

 his works on probability, 394- 

 395 ; apparent sequence, 409 : 

 sub- equality, 480 ; rale of ap- 

 proximation, 481 ; negative areas, 

 529 ; generalisation, 600 ; double 

 algebra, 634 ; bibliography, 716 ; 

 catalogues, 716 ; extensions of 

 algebra, 758. 



Density, unit of, 316 ; of earth, 

 387 ; negative, 642. 



Descartes, vortices, 517 ; geometry, 

 632. 



Description, 62. 



Design, 762-763. 



Determinants, inference by, 50. 



Development, logical, 89, 97. 



Diagnosis, 708. 



Dichotomy, 703. 



Difference, 44 ; law of, 5 ; sign of, 

 17 ; representation of, 45 ; infer- 

 ence with, 52, 166 ; form of, 158. 



Differences of numbers, 185. 



Differential calculus, 477. 



Differential thermometer, 345. 



Diffraction of light, 420. 



Dimensions, theory of, 325. 



Dip-needle, observation of, 355. 



Direct deduction, 49. 



Direction of motion, 47. 



Discontinuity, 620. 



Discordance, of theory and experi- 

 ment. 558 ; of theories, 587. 



Discoveries, accidental, 529 pre- 

 dicted, 536 ; scope for, 752, 



Discrimination, 24 ; power of, 4. 



Disjunctive, terms, 66; conjunction, 

 67 ; propositions, 66 ; syllogism, 

 77 ; argument, 106. 



Dissipation of energy, 310. 



Distance of statements, 144. 



Divergence from average, 188. 



Diversity, 156. 



Divine interference, 765. 



Dollond, achromatic lenses, 608. 



Donkin, Professor, 375 ; on proba- 

 bility, 199, 216 ; principle o, 

 inverse method, 244. 



Double refraction, 426. 



Dove's law of winds, 534. 



Draper's law, 606. 



Drobitsch, 15. 



Duality, 73, 81 ; law of, 5, 45, 92, 

 97. 



Dulong and Petit, 341, 471. 



Duration, 308. 



e, 330, 769. 



Earth, density of, 387 ; ellipticity, 



565. 

 Eclipses, 656 ; Egyptian records of, 



246 ; of Jupiter's satellites, 294, 



372 ; solar, 486. 

 Electric, sense, 405 ; acid, 428 ; 



fluid, 523. 

 Electric telegraph, anticipations of, 



671. 

 Electricity, theories of, 522; duality 



of, 590. 



Electrolysis, 428, 530. 

 Electro-magnet, use of, 423. 

 Elements, confusion of, 237 ; defini- 

 tion, 427 ; classification, 676, 



677, 690. 

 Elimination, 58. 



Ellicott, observation on clocks, 455. 

 Ellipsis, 41 ; of terms, 57. 

 Elliptic variation, 474. 

 Ellipticity of earth, 565. 

 Ellis, A. J., contributions to formal 



logic, 172. 



Ellie, Leslie, 23, 375. 

 Ellis, W., on moon's influence, 410. 

 Emanation, law of, 463. 

 Emotions, 732. 

 Empirical, knowledge, 505, 525- 



526 ; measurement, 552. 

 Encke, on mean, 386, 389; his 



comet, 570, 605 ; on resisting 



