PROGRESS OF ASTRONOMY FOR 1889, 1890. 



By William C. Winlock. 



The followiiij? record of astronomy for the years 1889 and 1890 is 

 presented in essentially the same form as its predecessors. The com- 

 piler has made free use of reviews, in the various branches of astronomy, 

 contributed by specialists to the Atliencvum. Nature, Journal of the As- 

 tronomical Society of the Pacijic. the Observatory, Bulletin Astronomique^ 

 the AstronomicalJournal, and other periodicals. 



NEBULA. 



Motions of the planetary nehulw in the line of sight. — No. 11 of the Pub- 

 lications of the Astronomical Society of the Pacific contains a very 

 important paper by Mr. James E, Keeler on the "Motions of the plan- 

 etary uebulse in the line of sight." The paper is an important one in a 

 twofold aspect: first, in its bearing on a matter just now under dis- 

 cussion by the highest authorities, as to the character and position of 

 the brightest nebular line, and secondly, in the evidence it affords of 

 nebuUir movements. 



As to the character of the nebular line, Mr. Keeler's testimony is 

 most emphatic, and entirely confirms Dr. Huggins's observations. "The 

 nebular lines," he reports, " appeared to be perfectly monochromatic 

 images of the slit, widening when the slit was widened and narrowing 

 to excessively fine sharp lines when it was closed up." The chief neb- 

 ular line " showed no tendency to assume the aspect of a remnant of 

 fluting under any circumstances of observation." This observation, 

 made not on one nebula, but on a number, and with a dispersion often 

 equivalent to that of 24 prisms of 60°, for the fourth spectrum of a 

 Rowland's grating of 14,438 lines to the inch was often used, is by far 

 the strongest evidence we liave yet had on this question of the charac- 

 ter of the chief nebular line, and it is dead against Mr. Lockyer's 

 theory. 



The position of the nebular line is also fixed with very considerable 

 certainty ; and here, again, Dr. Huggins's observations receive complete 

 confirmation. It was not, in any oue of the uebuhe observed, coincident 

 "with the fluting of magnesium, but was always seen some distance to 



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