Fig. 26. Feb. 7, 1836. 



Fig. 28. Feb. 10, 1836. 



HALLKY'S COMET DEPARTING FROM THE SUN IN 1836. 



COMETS. 



CHAPTEE III. 



Halley's prediction (continued). 55. Great advance of mathematical 

 and physical sciences between 1682 and 1759. 56. Exact path of 

 the comet on its return, and time of its perihelion, calculated and 

 predicted by Clairaut and Lalande. 57. Remarkable anticipation 

 of the discovery of Uranus. 58. Prediction x>f Hal ley and Clairaut 

 fulfilled by reappearance of the comet in 1758-9. 59. Disturbing 

 action of a planet on a comet explained. 60. Effect of the perturbing 

 action of Jupiter and Saturn on Halley's comet between 1682 and 

 1758. 61. Calculations of its return in 1835-36. 62. Predictions 

 fulfilled. 53. Elements of the orbit of Halley's comet. 64. Pons's 

 comet of 1812. 65. Olbers's comet of 1815. 66. De Vice's comet 

 of 1846. 67. Brorsen's comet of 1847. 68. Westphal's comet of 

 1852. 69. Data necessary to determine the motions of these six 

 comets. 70. Diagram of their orbits. 71. Planetary characters are 

 nearly effaced in these orbits. IV. ELLIPTIC COMETS, WHOSE MEAN 



DISTANCES EXCEED THE LIMITS OP THE SOLAR SYSTEM : 72. Synopsis 



of twenty-one elliptic comets of great eccentricity and long period. 

 73. Plan of the form and relative magnitude of the orbits. V. 74. 

 HYPERBOLIC COMETS : VI. 75. PARABOLIC COMETS. VII. PHYSICAL 

 CONSTITUTION OP COMETS : 76. Apparent form head and tail. 77. 



LIRDNER'S MUSEUM OF SCIENCE. 

 No. 140. 



177 



