56 



ASTRONOMICAL PROGRESS IN 1899. 



Nebulae. In four years of the five that Dr. 

 Lewis Swift has been director of the Lowe Ob- 

 servatory, at Echo Mountain, California, he has 

 discovered and catalogued 350 new nebuise. 

 Some of these are very interesting, and deserve 

 thorough investigation with the spectroscope 

 and the largest telescopes. Special attention is 

 drawn to a few, as follows: 



One which he calls a nebulous nebula, in right 

 ascension 23 h 29 m , declination south 30 29', has 

 the appearance of a central elongated nebula, 

 with sharp outline, centrally superimposed on 

 another very much the larger and of unimagined 

 faintness. It is probably the only one in the 

 heavens that bears any resemblance to it, and 

 raises the question whether there can be any 

 connection between the two, if two there are. 

 Astronomers are acquainted with several nebu- 

 lous stars that is, a star in the center of a nebu- 

 lous atmosphere but a nebula in the center of a 

 nebulous atmosphere is a novelty. One in right 

 ascension O h 46 45 s , declination south 35 0.5', 

 presents the curious aspect of a double nebulous 

 Uranus. Two others, which he calls hair-line 

 nebulae, resembles, except in color, a Miort piece 

 of horsehair. They are doubtless disk nebulae, 

 their thin edges being presented exactly to our 

 line of sight. Their places for A. D. 1900 are 

 right ascension 3 Tl 31 m , declination south 34 47', 

 and right ascension 5 h 29 m 20 s , declination south 

 36 28'. 



Prof. Herbert A. Howe, director of the Cham- 

 berlain Observatory, University Park, Colorado, 

 has recently discovered 22 new ones while ob- 

 taining micrometrical places of some previously 

 discovered. 



Dr. De Lisle Stewart has 46 novae on photo- 

 graph plates, taken with the Bruce photographic 

 telescope at the Harvard Observatory station, 

 Peru, in the latter part of 1898. The group is 

 between right ascension 3 h 10 m and 3 h 50 m , and 

 declination south 49 50' and 55 40'. Only two 

 appear in Dreyer's New General Catalogue of 

 Nebulae viz., 1311 and 1356. There are several 

 nebulous regions in the celestial vault that sug- 

 gest the idea that they may be offshoots from 

 one, or at least are connected together, the con- 

 necting links being invisible from faintness and 

 distance. Isaac Roberts has lately reproduced 

 a photograph of No. 2239, between right ascen- 

 sion 6 h 24 m and 6 h 23 m and north declination 

 4 24.8' and 5 56.5' in the constellation Mono- 

 ceros, with ,an exposure of 2 h 45 m , a depiction of 

 nebulosity, extending like a cloud, but broken up 

 into wisps, streamers, and curdling masses dense- 

 ly dotted with stars on its surface and the sur- 

 rounding region. Several remarkable black 

 tortuous rifts meander through the nebulosity, 

 their margins sharply delineated. 



Hind's variable nebula is the only well-au- 

 thenticated instance of a nebula varying in 

 brightness, somewhat analogous to variable stars. 

 It is in Taurus, and is No. 1555 of the catalogue 

 of nebulae. The following observations were 

 made with the 40-inch telescope of the Yerkes 

 Observatory by Dr. Barnard : When discovered by 

 Prof. Hind, of England, many years ago this 

 nabula was conspicuous in an ordinary telescope, 

 but in 1868 it had vanished from the largest tele- 

 scopes. Mr. Burnham saw it as a very faint 

 nebula, in 1890, in the 36-inch telescope at the 

 Lick Observatory. In February, 1895, it was an 

 easy object, but it had vanished the following 

 September. On Sept. 28, 1897, it could be de- 

 tected at good intervals of seeing, but with ex- 

 tremest difficulty, with the great Yerkes telescope. 



Dr. Scheiner, with an exposure of seven and a 



half hours, obtained a good photograph of the 

 spectrum of the great nebula in Andromeda from 

 F to H. A comparison between this and the solar 

 spectrum disclosed a surprising agreement be- 

 tween them. No trace of bright lines (a sure 

 indication of the presence of gas) was present, 

 so that the interstellar space in the nebula is not 

 apparently occupied by gaseous matter. The 

 doctor calls attention to the analogy between the 

 Andromeda nebula and the Milky Way. The 

 streams and irregularities of the latter he re- 

 gards as of special structure, instead of a ring 

 system. The ground for this view is the fact 

 that all ring nebuise give gaseous spectra, in 

 contrast with the spiral nebula. 



Dr. J. E. Keeler, director of the Lick Observa- 

 tory, on the night of Dec. 12, 1898, observed the 

 Orion nebula with the spectroscope attached to 

 the 36-inch telescope. The slit was first placed 

 on the nebulosity surrounding the star (Bond 

 734). The night being hazy, only a single line 

 was visible, identified as H/3. The slit was then 

 placed on the Huyghenian region near the tra- 

 pezium, which showed the usual spectrum, fl/3 

 and the second nebular line (a) =4959 were 

 about equally bright, but the chief line (a) = 5007 

 was several times brighter than either. The in- 

 tensity of the spectrum was then diminished by 

 contracting the vertical aperture of the spectro- 

 scope, the resolving power remaining unchanged. 

 When the brightness was sufficiently reduced Hj8 

 and the second line disappeared, the chief nebular 

 line alone being visible. In other words, with a 

 sufficiently feeble spectrum the Hj8 line was alone 

 visible in one part of the nebula, and the chief 

 line alone in another part. The doctor pronounces 

 the result inexplicable on physiological grounds, 

 and thinks it can only be due to real difference 

 in the spectrum of the nebula itself. 



Recent observations of the star Mira (which 

 varies from the second magnitude to invisibility 

 in eleven months) by Prof. Campbell, with the 

 Mills spectrograph attached to the 36-inch tele- 

 scope at the Lick Observatory, show that the 

 star is retrograding from us at the rate of 38.5 

 miles a second. This result was obtained from 

 the dark lines only, as some of the bright lines 

 show considerable displacement toward the vio- 

 let. He was unable to perceive any trace of the 

 green line of hydrogen, yet the two succeeding 

 members glowed with unexpected intensity. The 

 absence of the lower radiations constitutes an 

 anomaly of the most pronounced kind, and is 

 accounted for by the diverse character of the 

 hydrogen spectrum in nebulae and bright helium 

 stars. 



Comets. In 1898 ten comets were observed, 

 one more than ever before recorded, while up to 

 Oct. 20 three only were discovered in 1899, and 

 two of these were expected. 



Comet 1 1898 (Brooks). This interesting comet 

 was discovered by William R. Brooks at Smith 

 Observatory, Geneva, N. Y., on Oct. 20, 1898, in 

 the constellation Draco, in right ascension 14 h * 

 35m iQs, declination north 60 26'. For a tele- 

 scopic comet it was large and bright, being visi- 

 ble with a 3-inch telescope, in presence of a half- 

 moon. For a while after discovery it was sup- 

 posed to be a return of Schaeberle's comet of 

 1881 IV, so similar were their orbital elements. 

 Further observations, continued longer, afforded 

 evidence that it was moving in a parabola, and 

 therefore was a visitor to our system for the 

 first and last time. Similarity of element, how- 

 ever, leads strongly to the supposition that 

 they belong to the same family. The follow- 

 ing are the latest, and presumably the most ac- 



