CHAP. IX. OF THE CLASSIFICATION OF SCIENCES 136 _Art._ 1. Use and Limits of such Classification. 2. Classification depends on the Ideas. 3. This points out Transitions. 4. The Classification. INDUCTIVE TABLE OF ASTRONOMY 140 INDUCTIVE TABLE OF OPTICS 140 BOOK III. OF METHODS EMPLOYED IN THE FORMATION OF SCIENCE. CHAP. I. INTRODUCTION 141 _Art._ 1. Object of this Book. 2. An Art of Discovery not possible. 3. Use of Methods. 4. Series of Six Processes. 5. Methods of Observation and Induction. CHAP. II. OF METHODS OF OBSERVATION 145 _Art._ 1. Referring to Number, Space, and Time. 2. Observations are never perfect. 3. (I.) _Number is naturally exact_. 4. (II.) _Measurement of Space_. 5. Instruments Invented in Astronomy, 6. And improved. {xviii} _Art._ 7. Goniometer. 8. Standard of Length. 10. (III.) _Measurement of Time_. 11. Unit of Time. 12. Transit Instrument. 13. Chronometers. 14. (IV.) _Conversion of Space and Time_. 15. Space may Measure Time. 16. Time may Measure Space. 17. (V.) _The Method of Repetition_. 18. The Method of Coincidences. 19. Applied to Pendulums. 20. (VI.) _Measurement of Weight_. 21. Standard of Weight. 22. (VII.) _Measurement of Secondary Qualities_. 23. "The Howl" in Harmonics. 24. (VIII.) _Manipulation_. 25. Examples in Optics. 26. (IX.) _The Education of the Senses_, 27. By the Study of Natural History. 28. Preparation for Ideas. CHAP. III. OF METHODS OF ACQUIRING CLEAR SCIENTIFIC IDEAS; _and first_ OF INTELLECTUAL EDUCATION 164 _Art._ 1. (I.) _Idea of Space_. 2. Education by Geometry. 3. (II.) _Idea of Number_. 4. Effect of the usual Education. 5. (III.) _Idea of Force_. 6. Study of Mechanics needed, 7. To make Newton intelligible. 8. No _Popular_ Road. 9. (IV.) _Chemical Ideas_. 10. (V.) _Natural History Ideas_. 11. Natural Classes to be taught. 12. Mathematical Prejudices, 13. To be corrected by Natural History. 14. Method of Natural History, 15. Resembles common language. {xix} _Art._ 16. Its Lessons. 17. (VI.) _Well-established Ideas alone to be used_. 18. How are Ideas cleared?