A ROUND NEBULA, OBSERVED AND DRAWN THE SAME OBJECT, AS SHOWN IN LORD 



BY SIR J. HERSCHEL. ROSSE'S GREAT TELESCOPE. 



THE STELLAR UNIVERSE. 



CHAPTEE 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 discovered by Mr. Hind. 47. Missing 

 stars. DOUBLE STARS : 48. Researches of Sir W. and Sir J. Herschel. 

 49. Stars optically double. 50. This supposition not admissible. 

 51. Refuted 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. 



38. IN the preceding paragraphs, our observations have been 

 limited to those stars which are visible to the naked eye. But 

 the power of the telescope to augment in an indefinite proportion 

 the light received by the eye from such an object, obviously sup- 

 plies the means of rendering stars visible, which, by reason of 

 their extreme distance, transmit light of too small a quantity to 

 affect the retina in any sensible degree. AVe have seen that stars 



* The objects are here drawn upon a larger scale than in the original 

 figures, in order to render their details more distinct. The same enlarge- 

 ment of scale has been made in figs. 17, 18, 19, 20, 29, 30, 41, 42, 43, 

 44, 45, 46, 57, 58. 



LARDNER'S MUSEUM OP SCIENCE. o 193 



No. 90. 



