182 COSMOS. 



an opinion of the connection of forms in the universe, analo- 

 gous to the frequently misemployed doctrine of transition in 

 organic nature, was shared by Immanuel Kant, one of the 

 greatest minds of the eighteenth century. At two epochs, 

 twenty-six and ninety-one years after the Naturgeschichte 

 des Himmels was dedicated to the great Frederick by the 

 Konigsberg philosopher, Uranus and Neptune were discovered 

 by William Herschel and Galle ; but the orbits of both plan- 

 ets have a less degree ^of eccentricity than that of Saturn ; 

 if even the latter is 0*056, so, on the contrary, Neptune, the 

 outermost of all known planets, moves in an orbit whose ec- 

 centricity is 0*008, nearly the same as that of Venus (0.006). 

 In addition to this, Uranus and Neptune present none of the 

 predicted cometary characters. 



As, in more recent times (since 1819), the discovery of 

 Encke's Comet was gradually followed by those of five inte- 

 rior comets, forming, as it were, a peculiar group, the semi- 

 major axis of whose orbits for the most part resembles those 

 of the small planets, the question was raised as to whether 

 the group of interior comets may not, as is conjectured by 

 Gibers, in his hypothesis respecting the small planets, origin- 

 ally have formed a single cosmical body ; whether the large 

 comet may not have been separated into several by the influ- 

 ence of Mars, in the same way that such a separation, as it 

 were a bipartition, took place under the eye of the observer 

 in the year 1846, on the occasion of the last return of the 

 interior comet of Biela. Certain similarities in their elements 

 have induced Professor Stephen Alexander, of the College of 

 New Jersey, to institute investigations* as to the possibility 



Kant, " the last planets beyond Saturn would gradually pass into com- 

 ets, and so the last species would be connected with the first. The law 

 according to which the eccentricity of the planetary orbits is propor- 

 tionate to the distances of the planets from the Sun, supports this con- 

 jecture. The eccentricity increases with the distance, and, consequent- 

 ly, the more distant planets approach nearer to the definition of com- 

 ets. The last planet and the first comet may be called that body which 

 in its perihelion intersects the orbit of the adjoining planet, perhaps 

 that of Saturn. Our theory of the mechanical formation of the cosmical 

 bodies is also clearly proved by the magnitudes of the planetary masses 

 which increase with the distance from the Sun." Kant, Naturge- 

 schichte des Himmels (1755), in his Sdmmtliche Werke, th. vi., p. 88 and 

 195. At the commencement of the fifth section (p. 131), he speaks of 

 the former cometary nature which Saturn was supposed to have pos- 

 sessed. 



* Stephen Alexander, "On the Similarity of arrangement of the As- 

 teroids and the Comets of short period, and the possibility of their 

 common origin." in Gould's Astronom. Journal, No. 19, p. 147, and No. 



