vi CONTENTS. 



THE THERMOMETER. 



PAGE 



Heat. 2. Sensible heat. 3. Latent heat. 4. Contraction and 

 dilatation. 5. Liquefaction and solidification. 6. Vaporisation 

 and condensation. 7. Incandescence. 8. Combustion. 9. 

 Temperature. 10. Conduction. 11. Radiation. 12. Some 

 bodies are pervious to heat. 13. Some reflect heat. 14. Means 

 of measuring the degrees of heat. 15. Mercurial thermometer. 

 16. Preparatidh of mercury. 17. Selection of tube. 18. 

 Formation of bulb. 19. How the tube is filled. 20. Scale 

 applied. 21. Graduation of scale. 22. Zero point. 23. Stan- 

 dard points. 24. Freezing and boiling temperatures universally 

 adopted. 25. Fahrenheit's scale. 26. Centigrade. 27. Reau- 

 mur's. 28. Increase of volume of mercury. 29. Uniformity of 

 its dilatation. 30. Standard thermometer. 31. Range of scale. 

 32. Why mercury is employed in thermometers. 33. Self- 

 registering thermometers. 34. Alcohol thermometers. 35. Air 

 thermometer. 36. Differential thermometer . . . .145 



THE NEW PLANETS. 



Discovery of these planets. 2. The old planets. 3. Numerical 

 law of their distances. 4. A missing planet. 5. Conjecture of 

 Professor Bode. 6. Discovery of Ceres. 7- Of Pallas. 8. 

 Theory of Dr. Olbers a broken planet. 9. Discovery of Juno. 

 10. Of Vesta. 11. Rapid discovery of the others. 12. Table 

 of the group. 13. Circumstances corroborating the theory of 

 Dr. Olbers. 14. Amateur astronomers. 15. Minute bulk of 

 these planets. 16. Corroboratory of Dr. Olbers' theory. 17. 

 Force of gravity upon them 161 



LE VERRIER AND ADAMS' PLANET. 



1. Surprise excited by the discovery. 2. How a body may be dis- 

 covered without seeing it. 3. Generalisation of the principle. 

 4. Its application to the case of Neptune. 5. Condition of 

 the solar system before the discovery. 6. Observed disturbances 

 of Uranus. 7. Great regularity of these effects. 8. How they 

 would be produced by a more distant planet. 9. Calculations 

 of Le Verrier and Adams. 10. Elements of the sought planet 

 according to these geometers. 11. Its actual discovery. 12. 

 Its corrected elements. 13. Discrepancies between the actual 

 and predicted elements explained. 14. Comparison of the effects 

 of the real and predicted planets. 15. The discovery not to be 

 ascribed to chance. 16. The period of Neptune computed. 17. 

 Computation of his distance. 18. Its prodigious orbital motion. 

 19. Illustrated by a railway train. 20. Its magnitude. 21. 

 Its satellite. 22. Its weight. 23. Its bulk. 24. The sun's 

 light and heat upon it. 25. The sun's apparent diameter seen 

 from it. 26. Its suspected ring 171 



