CONTENTS. IX 



a stronger one, p. xviii. Note 104. Apparent "rays" pro- 

 ceeding from stars, p. 50 and 109 111. On the visibility of 

 Jupiter's satellites with the naked eye, p. 49 and xix. xx. 

 Note 105. Fluctuation of stars, p. 55 56, and 453, and xxii. 

 Note 113. Commencement of telescopic vision, and its appli- 

 cation to measurement, p. 58 60 and 63. Refractors of great 

 length, p. 60 and xxiii. Notes 115118. Reflectors, p. 61 64 

 and xxiii. xxiv. Notes 119123. Observations in the day- 

 time, and how high magnifying powers facilitate the finding of 

 stars during daylight, p. 656? and xxiv. Note 127. Expla- 

 nation of the sparkling, or scintillation, of stars and other 

 heavenly bodies, p. 67 71 and xxvii. xxx. Notes 129136. 

 Velocity of light, p. 7178 and xxx. xxxv. Notes 137149. 

 Arrangement of stars according to their apparent magnitudes ; 

 photometric relations and methods of measurement, p. 78 85 

 and xxxvi. Notes 156 166. Cyanometer, p. xxxix. Pho- 

 tometric arrangement of the fixed stars, p. xl. xlv. 



III. Number, Distribution, and Colour of the Fixed Stars Clusters 

 of Stars and Milky Way. Conditions of the sky favourable or 

 uufavourable to the recognition of stars, p. 86 88. Number 

 of stars, and how many are visible to the unassisted eye, p. 88. 

 How many stars have had their places determined, and have 

 been entered in star-catalogues or star-maps, p. 88 100 and 

 xlvi. lii. Notes 170 190. Approximate estimation hazarded 

 respecting the number of stars which may be visible in the en- 

 tire heavens with the present space-penetrating telescopes, 

 p. 99 100. Contemplative astrognosy among rude nations, 

 p. 100 102. Greek celestial sphere, p. 102105 & lii. liv. 

 Notes 193199. Crystal sphere, p. 106108 and liv. Ivi. 

 Notes 200203. Factitious diameters of the fixed stars as 

 seen in telescopes, p. 109 111. Smallest object which can be 

 distinctly perceived in the heavens by the aid of telescopes, p. 

 Ill and Ivii. Note 211. Differences of colour in stars, and 

 alteration of colour within historic times, p. Ill 115 and 

 Iviii. Ixi. Notes 212218. Sinus (Sothis) p. 112114 and 

 lix. hi. Note 218. The four "royal stars," p. 115. Gra- 

 dually acquired knowledge of the southern heavens, p. 116 



