ASTEONOMIOAL PROGRESS AND DISCOVERY. 



In a 4-inch telescope it appeared as a small, 

 bright, nebulous star, without a nucleus. It 

 was moving rapidly both east and south. This 

 comet was originally discovered on Nov. 26, 

 1818, by the astronomer Pons, at Marseilles. 

 It was then viable for seven weeks. Prof. 

 Encke, of Berlin, subjected the observations 

 to a careful investigation, and showed that the 

 orbit was elliptical, with a period of about 

 three and one third years. He identified the 

 comet witb the comets of 1786 I, 1795, and 

 1805, and predicted its return. His calcula- 

 tions were almost exactly fulfilled. Ordina- 

 rily it appears to have no tail. In 1848 it 

 had two, one about 1 in length directed from 

 the sun, and the other a little shorter, and 

 turned toward it. At perihelion the comet 

 passes within the orbit of Mercury, and at 

 aphelion its distance from the sun is about 

 equal to that of Jupiter. Investigations of the 

 motions of this comet show that its period is 

 steadily diminishing by about two and a half 

 hours in every revolution. Encke's theory 

 was that the comet, in moving through space, 

 met with a resistance from some rare medi- 

 um, which was not able to impede the great- 

 er masses of the planets. Many astronomers 

 are inclined to doubt the existence of a re- 

 sisting medium ; but lately, Dr. Backlund, the 

 Swedish astronomer, from an examination of 

 the observations of the comet between 1871 

 and 1881, concludes that there is a retardation, 

 although the amount is less than that assigned 

 by Encke. No other comet seems to be re- 

 tarded, so that if we accept the theory of a re- 

 sisting medium we must imagine that it does 

 not extend very far from the sun. The in- 



1843. It had a bright nucleus and short tail, 

 but was not visible to the naked eye. Lever- 

 rier investigated its orbit, and predicted its re- 

 turn to perihelion on April 3, 1851. It returned 

 within a day of the time predicted. Its peri- 

 helion distance is about 100,000,000 miles, and 

 its aphelion distance about 500,000,000 miles. 



Comet V was discovered on September 2, 

 by E. E. Barnard, at the Lick Observatory. It 

 was described as circular, I' in diameter, elev- 

 enth magnitude, with a well-defiued nucleus. 

 No decided motion was observed in twenty 

 minutes. Prof. Boss calculated the provisional 

 elements given in the table, which show that 

 the theoretical brightness at perihelion would 

 be about seventy times the brightness at dis- 

 covery. The same observer furnishes the fol- 

 lowing notes: 



September 5. The comet has a soft but condensed 

 light. The coma is somewhat less than 30" in diame- 

 ter, and symmetrical. The condensation is very uni 

 form toward the center, without a distinct nucleus 

 Under illumination the central parts some 5" in di 

 ameter appear as a star of 11'5 magnitude. 



September 6. There is a very small nucleus of about 

 the thirteenth magnitude. 



September 10. The nebulosity is elliptical, with 

 axes of about 40" and 60" respectively. Nuclear con- 

 densation well marked, and is, perhaps, 10" south of 

 the center of the nebulous mass. 



Comet VI was discovered by E. E. Bar- 

 nard, at Lick Observatory, October 31. He 

 describes it as having no tail, a strong central 

 condensation, of the eleventh magnitude, or 

 fainter ; the nebulosity was 1' in mean diame- 

 ter, and was much elongated. 



We give the approximate elements of these 

 comets in the following table : 



vestigations of Mr. Sherman seem to point in 

 the same direction as those of Dr. Backlund. 



Cornet III was discovered by W. R. Brooks, 

 of Geneva, N. Y., August 7. On August 10, 

 Prof. Boss reported the comet as small and 

 condensed, and showing, with low powers, as 

 a star of the ninth magnitude. It had a short 

 tail with an estimated length of 10', and of the 

 same breadth as the head. It had already 

 passed perihelion when discovered, and was 

 rapidly diminishing in brightness. It was 

 thought that observations might be made up 

 to the October moon. 



Comet IV was found at Nice Observatory 

 on August 9. The ephemeris shows that the 

 comet is slightly increasing in brightness. 

 This comet is one of the short-period comets. 

 Its last appearance was in 1880; its period is 

 7'4 years. The present is its seventh appear- 

 ance. This comet was first discovered by M. 

 Faye, at the Paris Observatory, on Nov. 22, 



W. F. Denning says that fourteen comets 

 were discovered between 1827 and 1836, while 

 between 1877 and 1886 forty-nine were dis- 

 covered. In seven years E. E. Barnard and 

 W. R. Brooks have discovered twenty com- 

 ets ten apiece and to the end of 1887 

 they had received $2,700 in prizes. In the 

 September number of " The Observatory," T. 

 W. Backhouse gives the following interesting 

 table in regard to naked-eye comets seen since 

 1881: 



