198 r lHK POPULAR SCIENCE MONTHLY. 



We turn our five-inch telescope, armed with a low magnifying 

 power, upon this object and enjoy a rare spectacle. As we allow it 

 to drift through the field we see a group of three comparatively 

 brilliant stars advancing at the front of a wonderful train of 

 mingled star clusters and nebulous clouds. A little northwest of 

 it appears the celebrated trifid nebula, No. 4355 on the map. 

 There is evidence that changes have occurred in this nebula since 

 its discovery in the last century. Barnard has made a beautiful 

 photograph showing M 8 and the trifid nebula on the same plate, 

 and he remarks that the former is a far more remarkable object 

 than its more famous neighbor. Near the eastern border of the 

 principal nebulous cloud there is a small and very black hole 

 with a star poised on its eastern edge. This hole and the star are 

 clearly shown in the photograph. 



Cluster No. 4397 (M 24) is usually described as resembling, to 

 the naked eye, a protuberance on the edge of the Milky Way. It 

 is nearly three times as broad as the moon, and is very rich in 

 minute stars, which are just at that degree of visibility that 

 crowds of them are continually appearing and disappearing while 

 the eye wanders over the field, just as faces are seen and lost 

 again in a vast assemblage of people. This kind of luminous 

 agitation is not peculiar to M 24, although that cluster exhibits 

 it better than most others do on account both of the multitude 

 and the minuteness of its stars. 



A slight sweep eastward brings us to yet another meeting 

 place of stars, the cluster M 25, situated between the variables U 

 and V. This is brilliant and easily resolved into its components, 

 which include a number of double stars. 



The two neighboring variables just referred to are interesting. 

 U has a period of about six days and three-quarters, and its range 

 of magnitude runs from the seventh down to below the eighth. 

 V is a somewhat mysterious star. Chandler removed it from his 

 catalogue of variables because no change had been observed in its 

 light by either himself, Sawyer, or Yendell. Quirling, the dis- 

 coverer of its variability, gave the range as between magnitudes 

 7"6 and 8*8. It must, therefore, be exceedingly erratic in its 

 changes, resembling rather the temporary stars than the true 

 variables. 



In that part of Scutum Sobieskii contained in map jSTo. 12 we 

 find an interesting double, 2 2325, whose magnitudes are six and 

 nine, distance 12"3", p. 260, colors white and orange. 2 2306 is a 

 triple, magnitudes seven, eight, and nine, distances 12", p. 220, 

 and 0'8", p. 08. The third star is, however, beyond our reach. 

 The colors of the two larger are respectively yellow and violet. 



The star cluster 4400 is about one quarter as broad as the 

 moon, and easily seen with our smallest aperture. 



