ASTRONOMY, PROGIIKSS OF, IN 1892. 



39 



Dr. Iluggins. wlio with Mrs. Unpins mail.' 

 speetn>M-,.pir examination of the Nova on 1-Vli. 

 j. -ays, in Aatronomisehe Aacfirichten, No. 

 :!()?!: "The iiio-t noticeable feature to the eye 

 of the star's spectrum was the great brilliancy 

 of the hydrogen lines at C, F, and (i, with three 

 lines on the left side F, but the point of greatest 

 interest was obviously that each bright hydrogen 

 line was accompanied by a strong absorption 

 (dark) line toward the blue. Comparison with 

 the lines of terrestrial hydrogen showed at once 

 a large motion of recession of the bright lines, 

 and a motion of approach of the hydrogen which 

 produced the absorption. 



" A photograph which we have taken since 

 gives the star's spectrum as far as the ultra- 

 violet, or about wave length 3,200. Besides the 

 hydrogen series there are other lines doubled in 

 a similar manner, including the sodium lines at 

 D. The whole visible and photographic regions 

 from below C to about wave length 3,200 are 

 full of dark and bright lines. There is a bright 

 line a little more refrangible than D, which may 

 be D, and there are bright lines near C." 



Prof. Pickering says of eighteen photographs 

 of this region taken with the 8-inch photo- 

 graphic telescope, from Nov. 3, 1885, to Nov. 2, 

 1891, that on none was the star visible, nor on 

 plates obtained on thirteen nights from Oct. 21 

 to Dec. 1, 1891, although Chi Auriga was always 

 clearly shown. On twelve nights, beginning 

 Dec. 10, 1891, and ending Jan. 20, 1892, similar 

 plates were obtained, on all of which the new 

 star was plainly seen. He further adds : " It ap- 

 pears that the star was fainter than the eleventh 

 magnitude on Nov. 2, and fainter than the sixth 

 magnitude on Dec. 10. Its brightness increased 

 rapidly until Dec. 18, attaining its maximum 

 about Dec. 20, when its magnitude was 4*4. It 

 then began to decrease slowly until Jan. 20, 

 when it was somewhat below the fifth magni- 

 tude." All these changes occurred before its 

 discovery by Mr. Anderson. 



The doubling of the lines of the spectrum is a 

 fact of great interest and indicates that the star 

 is a close spectroscopic double, and that this 

 doubling is caused by the coincidence of the 

 approach of one with the recession of the other. 

 Dr. Vogel. of Potsdam, asserts that both the 

 bright and dark lines are double, and advances 

 the hypothesis that there are three bodies, two 

 of them circling around the third. lie esti- 

 mates the star with the bright-line spectrum to 

 be receding from the earth at the rate of 300 

 miles per second. 



The cause of the sudden increase in brightness 

 of stars, eighteen instances of which have been re- 

 corded during the last eighteen hundred years, is 

 unknown. Great interest is excited among as- 

 tronomers by their effulgence, and the literature 

 on the subject, especially on the Auriga Nova, is 

 abundant ; but for want of space only a few of 

 the most interesting facts can be alluded to. 

 All the theories advanced for the appearance of 

 temporary stars seem to be set at naught by an 

 announcement from Prof. Barnard that, seen 

 wit ii the 36-inch telescope, the Nova has changed 

 into a nebula with a stellar nucleus of about 

 the tenth magnitude. The nebulosity was 3" in 

 diameter, surrounded by a fainter glow of half a 

 minute in diameter. 



Variation of Latitude. In Nos. 251, 271, 

 and 272 of Gould's Agronomical Journal" 

 Prof. S. C. Chandler has nublishod a series of 

 papers on the variation of latitude which he has 

 detceted. and presents apparently invulnerable 

 j) roofs of the correctness of his conclusions. JI<> 

 finds the variation to point to a revolution of 

 the earth's axis of inertia about that of rotation 

 from west to east, in a period of four hundred 

 and twenty-seven days, with a radius of 30 feet 

 measured at the earth's surface. Though at 

 first sight his deductions seem unwarranted, yet 

 he has fortified them with facts which meet the 

 approbation of such mathematical astronomers 

 as Dr. B. A. Gould, Prof. Simon Newcomb, and 

 others. Dr. Gould, to confirm, if possible, the 

 truth of the theory, has examined the Cordoba 

 (Argentine Republic) observations, and finds 

 them corroboratory of Chandler's theory, though 

 he admits that the manifestations fluctuated ir- 

 regularly. This admission has a tendency to 

 weaken the testimony, but it would be rash to 

 condemn a theory having two such distinguished 

 adherents until the arguments on which it rests 

 are proved erroneous or insufficient. 



While the present period of revolution of the 

 pole of the earth's figure is supposed to be re- 

 volving around that of rotation in four hundred 

 and twenty-seven days, its period, about A. D. 

 1770, was less than a year, and since then has 

 been increasing. The evidence in support of 

 these conclusions is of so extensive a character 

 that not even an abstract can be given here. The 

 reader is referred to the original articles, which 

 will be found inteiesting reading. 



Rotation of Yenns and Mercury. It is 

 well known that Schiaparelfi, from' observations 

 continued through many years, has arrived at 

 the conclusion that, like our moon, both Mercury 

 and Venus rotate on their axes in the same time 

 in which they revolve around the sun, or Mer- 

 cury in eighty-eight, and Venus in two hundred 

 and twenty-five days. These ideas of the dis- 

 tinguished Italian astronomer do not meet with 

 general acceptance. M. Trouvelot, who has 

 for sixteen years studied these planets, thinks 

 that the original period of rotation of Venus, 

 as determined by the early astronomers, of not 

 far from twenty-four hours, is the correct one. 

 The equator is inclined only some 10 or 12 

 to the plane of its orbit, and the longitude of 

 the ascending node is 2. The poles are, as 

 others have supposed, crowned with lofty moun- 

 tains which rise above the dense and deep atmos- 

 phere of the planet. He decides that the irregu- 

 larities noticed by so many skillful observers at 

 the two extremities of the terminator are real, 

 and are due to the great elevation of the polar 

 mountains. 



M. Niesten. of the Brussels Observatory, as the 

 result of a long series of observations and draw- 

 ings, coincides with the views of Trouvelot and 

 sharply challenges those of Schiaparelli. The 

 observations necessary for the settlement of this 

 question are exceedingly difficult to make, and 

 hence it may require years of careful work and 

 many accurate drawings to decide the true rota- 

 tion periods of these planets. 



Opposition of Mars. The recent favorable 

 opposition of Mars was, as those for ages to come 

 will be, unfortunate for northern observers, from 



