PLEASURES OF THE TELESCOPE. i 97 



limits of map No. 12, both of which are more extensive than those 

 we have just been looking at. No. 4211 is 5' or 6' in diameter, 

 also globular, brighter at the center, and surrounded by several 

 comparatively conspicuous stars. No. 4340 is still larger, about 

 half as broad as the moon, and many of its scattered stars are 

 of not less than the ninth magnitude. With a low magnifying 

 power the field of view surrounding the cluster appears powdered 

 with stars. 



There are only two noteworthy doubles in that part of Ophiu- 

 chus with which we are at present concerned : 36, whose magni- 

 tudes are five and seven, distance 4*3", p. 195, colors yellow and 

 red ; and 39, magnitudes six and seven and a half, distance 12", 

 p. 356, colors yellow or orange and blue. The first named is a 

 binary whose period has not been definitely ascertained. 



The variable R has a period a little less than three hundred 

 and three days. At its brightest it is of magnitude seven or eight, 

 and at minimum it diminishes to about the twelfth magnitude. 



The spot where the new star of 1G04 appeared is indicated on 

 the map. This was, with the exception of Tycho's star in 1572, 

 the brightest temporary star of which we possess a trustworthy 

 account. It is frequently referred to as Kepler's star, because 

 Kepler watched it with considerable attention, but unfortunately 

 he was not as good an observer as Tycho was. The star was first 

 seen on October 10, 1G04, and was then brighter than Jupiter. It 

 did not, however, equal Venus. It gradually faded and in March, 

 1606, disappeared. About twelve degrees northwest of the place 

 of the star of 1604, and in that part of the constellation Serpens 

 which is included in map No. 12, we find the location of another 

 temporary star, that of 1848. It was first noticed by Mr. Hind on 

 April 28th of that year, when its magnitude was not much above 

 the seventh, and its color was red. It brightened rapidly, until on 

 May 2d it was of magnitude three and a half. Then it began to 

 fade, but very slowly, and it has never entirely disappeared. It 

 is now of the twelfth or thirteenth magnitude. 



In passing we may glance with a low power at v Serpentis, a 

 wide double, magnitudes four and nine, distance 50", p. 31, colors 

 contrasted but uncertain. 



Sagittarius and its neighbor, the small but rich constellation 

 Scutum Sobieskii, attract us next. We shall first deal with the 

 western portions of these constellations which are represented on 

 Map No. 12. The star ^ in Sagittarius is a wide triple, magni- 

 tudes three and a half, nine and a half, and ten, distances 40", p. 

 315, and 45", p. 114. But the chief glory of Sagittarius (and the 

 same statement applies to Scutum Sobieskii) lies in its assemblage 

 of star clusters. One of these, No. 4361, also known as M 8, is 

 plainly visible to the naked eye as a bright spot in the Milky Way. 



