ASTRONOMICAL PHENOMENA AND PROGRESS. 



41 



There can be little doubt but that in the observed 

 stellar movements we have to do with two other inde- 

 pendent motions, namely, a movement common to 

 certain groups of stars, and also a motion peculiar to 

 each star. 



Mr. Proctor has brought to light strong evidence 

 in favor of the drift of stars in groups having a com- 

 munity of motion, by his graphical investigation of 

 the proper motions of all the stars in the catalogues 

 of Mr. Main and Mr. Stone. 



Star-Depths. Mr. Richard A. Proctor has 

 delivered a series of lectures on the sidereal 

 universe, in London. He makes the following 

 statement (as briefly reported in the London 

 journals) of his views upon one of the astro- 

 nomical vexed questions of the day : 



The lecturer stated in the outset his belief that 

 not only are the stars not spread uniformly through- 

 out space, but that not even the general approach to 

 uniformity insisted upon in our treatises on astrono- 

 my in reality prevails. He would endeavor to show 

 that there are definite regions, within which stars 

 of many orders of magnitude are richly distributed, 

 while around these regions are vast spaces, in which 

 either there are no stars or stars are very sparsely 

 strewn. The first evidence quoted in favor of this 

 theory was the remarkable circumstance that the 

 southern hemisphere contains about 1,000 more stars 

 visible to the unaided eye than the northern. This 

 peculiarity is rendered more remarkable by the fact 

 that there is a well-marked northern rich region, as 

 well as a well-marked southern rich region of greater 

 extent. Now, in the British Association Catalogue, 

 there are about 5,600 stars included within the classes 

 visible to the naked eye. Yet when these stars are 

 shown in a series of twelve maps overlapping each 

 other uniformly, and each covering a space equal to 

 the tenth part of the heavens, instead of each map 

 showing about 560 stars, we find the north-polar map 

 showing 700, other five northern maps containing 

 400, 540 (a map crossed by Milky Way), 400, 370, 

 and 550 (another Milky-Way map) ; while the south- 

 polar map contains 1,130, and other five southern 

 maps contain 520, 890, 510, 590, and 570, the conden- 

 sation in all these southern non-polar maps being 

 markedly toward the south. The lecturer then pass- 

 ed to the star-gauges of the Ilerschels, and the prin- 

 ciple of star-gauging ; remarking that the regions sur- 

 veyed by the Herschels in this manner were exceed- 

 ingly limited, that the principle of the method was 

 hypothetical, and that tested by results it was shown 

 to be erroneous. Moreover, the elder Herschel (as 

 Struve pointed out) definitively abandoned the prin- 

 ciple or star-gauging. Passing to the labors of W. 

 Struve, the lecturer remarked that while they clearly 

 showed that the " grindstone theory " of the sidereal 

 universe is erroneous ; Struve pushed the method of 

 average-taking too far (" to the verge of audacity ") 

 in converting a zone of the heavens 30 wide round 

 the equator into an equatorial flat disk. The lecturer 

 then proceeded to discuss the proper motions of the 

 stars, showing thst they also indicate that the stars 

 are gathered into certain regions of space, and segre- 

 gated from others. He pointed out that Madler's 

 theory of a central sun (supposed by the German as- 

 tronomer to be recognizable in Alcyone of the Plei- 

 ades) is untenable, simply because the evidence 

 which Madler sought for only in Taurus the con- 

 currence of proper motions exists in at least an 

 equally well-marked degree in Gemini, and else- 

 where in the heavens. Sir John Herschel, Prof. 

 Grant, and others, had already pointed out that Mad- 

 ler's hypothesis was based on insufficient evidence. 

 The concurrence of colors in certain stellar groups, 

 as of greenish-white stars in Orion, and yellowish 

 stars in Cetus, was adduced as further evidence of 

 the laws according to which the stars are arranged. 

 Mr. Proctor remarked further that the variable stars 



are in nearly all cases placed where star-streams or 

 star-clusterings can be recognized, and that all tem- 

 porary stars have appeared within the Milky Way, 

 except the " Blaze Star "of 1866, which, however, 

 occupied a portion of the telescopic extension of the 

 Milky Way. He suggested, in explanation of this 

 remarkable circumstance^ that probably the occur- 

 rence of the outburst indicated by the appearance of 

 a new star is associated with the fact that in the 

 Milky Way there is a great abundance of unattached 

 cosmical matter, downfalls of which produce the dis- 

 plays in question. 



The Star Eta Argus. By means of the 

 great Melbourne telescope, the remarkable 

 changes in the nebula around the star Eta Argus 

 have been recently studied with a success never 

 attained by other instruments. Mr. McGeorge, 

 the observer, has made a series of sketches, 

 showing the modifications in the apparent 

 shape of the nebula. These were taken at in- 

 tervals of about three months, and exhibit 

 radical alterations in the structure of the ob- 

 ject. At one observation, the star which Her- 

 schel saw involved in dense nebula was seen 

 on the bare sky, the nebula having disap- 

 peared for some distance around it. The nu- 

 cleus of the formation proves to be a triple 

 star. Mr. McGeorge finds, as Lord Rosse did, 

 that high powers, on a good night, bring out 

 details of nebula invisible with lower powers. 

 On one occasion he speaks of using 1,300, 

 whose definition, he says, "was magnificent 

 for an hour." He notices a sort of stereoscopic 

 effect, which, particularly with the high pow- 

 ers, makes the Lemniscate look "like a huge 

 snowy cave with uneven woolly sides." 



In December, 1869, the spectrum of Eta 

 Argus showed bright lines ; but in January, 

 1871, there was no trace of them; but Mr. 

 McGeorge thought that with a wide slit he de- 

 tected absorption bands in the position of the 

 usual nebular lines. Distinct nebulosity was 

 then visible round the star, most condensed near 

 it, chiefly in the direction of the Lemniscate. 



It it, perhaps, unnecessary to remark that 

 Mr. McGeorge has seen nothing in the way of 

 colored stars at all to be likened to Kappa 

 Crucis ; one or two are reddish. 



It is the intention of the Melbourne astrono- 

 mers to pursue unremittingly the study of this 

 nebula, which seems already to have given 

 them such results. But it is evidently a most 

 laborious task which they have imposed on 

 themselves. At present they are confining 

 their attention to the vicinity of the Lemnis- 

 cate, but even there the field of labor is im- 

 mense, for already they have noticed three 

 times as many stars as were seen by Herschel. 



Spectroscopic Study of Nebula. D' Arrest, 

 in the Astronomische Nachrichten, gives the 

 results of his observations on two well-known 

 nebulse, one in Gemini and the other in Draco. 

 The first mentioned, according to D'Arrest, 

 belongs to the order of gaseous nebula. Its 

 light is almost wholly monochromatic, and is 

 concentrated in the nitrogen line. The bright 

 nucleus is not stellar, as had been supposed. 



