16 



Residual Differences between the Theoj'etical and Observed Longi- 

 tudes of Uranus, from the Theoi'ies of Peirce, Leverrier and 

 Adams. 





From Pei 



ce's Theory of 



Neptune, 











adopting for its Mass, 

















From l^ever- 



From 



From Lever- 











rier's origi- 



Adams' 



rier's best 







Tliat given by 



Struve's Mass 



nal Theory, 



Theory, 



Orbit for the 





That given by 



Bond's and 



derived from 



with his 



with his 



Modern Ob- 



Date. 



Bond's Obser- 



Lassell's 



his own Ob- 



Hypotheti- 



Second Hy- 



servations, 





vations of the 



Observations 



servations of 



cal Planet. 



pothetical 



without any 





Satellite. 



combined. 



Satellite. 





Planet, 



external 





1 



198 40 



1 



18 78 



1 







Planet. 



14494 



1845 



— 0.9 



— L2 



— 2.8 



— d'3 





+ 6.5 



1840 



— 1.1 



— ].3 



— 1.3 



+ 2.2 



+ l"3 



+ 0.7 



1835 



+ 2.0 



+ 2.4 



+ 3.9 



— 0.8 



— 1.2 



_ 4.5 



1829 



+ 0.8 



+ 1.3 



+ 2.5 



— 2.2 



+ 2.0 



— 7.3 



1824 



— 2.0 



— 1.9 



— 1.6 



— 5.4 



+ 1.7 



— 7.6 



1819 



+ 1.0 



+ 0.7 



+ 0.9 



+ 0.4 



— 2.2 



+ 3.8 



1813 



— 0.3 



+ 11 



— 2.3 



— 0.9 



— 1.0 



+ 4.5 



1808 



— 0.4 



— 0.6 



— 1.3 



+ 0.8 



0.0 



+ 3.8 



1803 



+ 0.8 



+ 1.2 



+ 3.2 



+ 0.8 



+ 1.6 



- 3.4 



1797 



+ 0.3 



+ 0.8 



+ 3.3 



— 1.0 



— 0.5 



— 6.7 



1792 



+ 0.3 



+ 0.5 



+ 1.6 



+ 0.3 



— 1.1 



— 7.8 



1787 



— 0.5 



— 1.2 



— 4.7 



— 1.2 



— 0.2 



+ 2.0 



1782 



— 3.0 



— 5.6 



— 18.3 



+ 2.3 



0.0 



+ 20.5 



% ri769 



— 6.0 



— 16.0 



— 67.0 



+ 3.7 



+ 1.8 



+ 123.3 



£ J 1756 



+ 4.0 



— 12.7 



—102.4 



— 4.0 



— 4.0 



+ 230.9 



c 1 1715 



+ 8.7 



+ 10.0 



— 99.6 



+ 5.5 



— 66 



+ 279 6 



< 1^1690 



+ 0.8 



+ 13.0 



—124.7 



—19.9 



+50.0 



+ 289.0 



BENJAMIN PEIRCE. 



Cambridge Observatory, March 23, 1843. 



Prof. Frazer read the following extract from a letter ad- 

 dressed to him by Prof. S. S. Haldeman, of Columbia. 



Columbia, Pa., Ath Sept. 1849. 

 Some time back I offered before the Philosophical Society an ex- 

 planation of the apparent projection of a star during occultation, upon 

 the disk of the moon, and the following experiment induces me to 

 believe it essentially correct. Let a pair of disks, having nearly the 

 same shade of colour, be placed so far from the eye as to render it 

 impossible to tell their relative distance. Let the edge of one (p) re- 

 presenting the planet, to which the eye is chiefly directed, be made 

 gradually to approach and to pass closely behind that representing 

 the moon (m), when it will be found that the impression of p re- 

 mains, while that of m envelopes it; that is, that the images become 

 confluent, and for a short period coexistent; particularly when the 



