Fig. 62. TELESCOPIC VIEW OF PART OF THE GREAT NEBULA IN THE 

 CONSTELLATION OF ARGO. 



THE STELLAR UNIVERSE. 



CHAPTEE II. 



12. Absence of parallax obstructed the acceptance of the Copemican 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 magnitude arbitrary. 22. Fractional magnitudes. 23. 

 Number of stars of each magnitude. 24. Total number of stars 

 in the firmament. 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 occupations. 29. Meaning of the term magni- 

 tude as applied to the stars. 30. Why the stars may be rendered 

 imperceptible by their distance. 31. Heal magnitudes of the stars. 

 32. Application of photometers or astrometers. 33. Comparison 

 of the sun's light with that of a star. 34. Relative 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. 



12. THE greatest difficulty against which the Copemican system 

 has had to struggle, even among the most enlightened of its oppo- 

 LAKDNER'S MUSEUM OP SCIENCE. N 177 



No. 88. 



