CONTENTS. vii 



THE STELLAR UNIVERSE. 



PACK 



CHAP. I. 1. Retrospect of the solar system. 2. Inquiries beyond 

 its limits. 3. This system surrounded by an extensive void. 

 4. This proved by the absence of external perturbations. 5. And 

 by comets, which are feelers of the system. 6. Where then is 

 the vast multitude of stars which appear in the firmament ? 

 7. Absence of apparent parallax. 8. Illustration of the effects 

 of parallax. 9. Its apparent absence favoured the Ptolemaic 

 system. 10. Effects of parallax explained. 11. Parallax of the 

 planets visible 169 



CHAP. II. 12. Absence of parallax obstructed the acceptance of the 

 Copernican system. 13. Immense distance of stars inferred from 

 its minuteness or absence. 14. Its greatest possible magnitude. 

 15. Distances of stars inferred. 16. Use of the motion of 

 light as a modulus of this distance. 17. Methods of ascertaining 

 the parallax. 18. Parallax of a Centauri. 19. Parallax of nine 

 principal stars. 20. The vacuum surrounding the solar system 

 necessary to cosmical order. 21. Classification of stars by magni- 

 tude arbitrary. 22. Fractional magnitudes. 23. Number of 

 stars of each magnitude. 24. Total number of stars in the fir- 

 mament. 25. Varieties of magnitude chiefly caused by difference 

 of distance. 26. Stars as distant from each other as from the 

 sun. 27. Telescopes do not magnify them. 28. Absence of a 

 disc proved by their occultations. 29. Meaning of the term mag- 

 nitude as applied to the stars. 30. Why the stars may be ren- 

 dered imperceptible by their distance. 31. Real magnitudes of 

 the stars. 32. Application of photometers or astrometers. 

 33. Comparison of the sun's light with that of a star. 34. Re- 

 lative real magnitudes of the sun and a star estimated. 35. 

 Comparative magnitude of the sun and the dog-star. 36. Vast 

 use of the telescope in stellar observations. 37. Its power to 

 increase the apparent splendour of a star explained . . .177 



CHAP. III. 38. Telescopic stars. 39. Space -penetrating power of 

 the telescope. 40. Vast distances of small telescopic stars. 

 PERIODIC STARS : 41. Stars of variable lustre. 42. Remarkable 

 stars of this kind in Cetus and Perseus. 43. Table of periodic 

 stars. 44. Hypothesis to explain periodic stars. TEMPORARY 

 STARS : 45. Such stars seen in ancient times. 46. Star dis- 

 covered by Mr. Hind. 47. Missing stars. DOUBLE STARS : 

 48. Researches of Sir W. and Sir J. Herschel. 49. Stars opti- 

 cally double. 50. This supposition not admissible. 51. Re- 

 futed by the proper motion. 52. Classification of double stars. 

 53. Table of double stars. 54. Coloured double stars. 55. 

 Triple and other multiple stars. 56. Attempt to discover 

 parallax by double stars. 57. Observations of Sir W. Herschel 193 



