ASTRONOMY WITH AN OPERA-GLASS. 517 



of its light becomes conspicuous when it is looked at with a glass. 

 The most inexperienced observer will hardly fail to be impressed by 

 the pure whiteness of El Nath, in comparison with which he will find 

 that many of the stars he had supposed to be white show a decided 

 tinge of color. The star in the tip of 

 the right, or southern horn, Zeta (^), is 

 remarkable, not on its own account, but 

 because it serves as a pointer to a famous 

 nebula, the discovery of which led Mes- 

 sier to form his catalogue of nebula?. 

 This is sometimes called the " Crab 

 Nebula," from the long sprays of nebu- 

 lous matter which were seen surrounding 

 it with Lord Rosse's great telescope. Our 

 little sketch is simply intended to enable 

 the observer to locate this strange object. 



_. , . - , . , The Crab Nebula. 



It he wishes to study its appearance, he 



must use a powerful telescope. But with a first-rate field-glass he can 

 see it as a speck of light in the position show'n in the cut, where the 

 large star is Zeta and the smaller ones are faint stars, the relative po- 

 sition of which will enable the observer to find the nebula, if he keeps 

 in mind that the top of the cut is toward the north. It is noteworthy 

 that this nebula for a time deceived several of the watchers who were 

 on the lookout for the predicted return of Halley's comet in 1835. 



And now let us look at the Hyades, an assemblage of stars not less 

 beautiful than their more celebrated sisters the Pleiades. The leader 

 of the Ilyades is Aldebaran, or Alpha Tauri, and his followers are 

 worthy of their leader. The inexperienced observer is certain to be 

 surprised by the display of stars which an opera-glass brings to view 

 in the Hyades. Our illustration will give some notion of their appear- 

 ance with a large field-glass. The " brackish poet," of whose rhymes 

 Admiral Smyth was so fond, thus describes the Hyades : 



"In lustrous dignity aloft see Alpha Tauri sMne, 

 The splendid zone he decorates attests the Power divine : 

 For mark around what glitt'ring orbs attract the wandering eye, 

 You'll soon confess no other star has such attendants nigh." 



The redness of the light of Aldebaran is a very interesting phe- 

 nomenon. Careful observation detects a decided difference between 

 its color and that of Betelgeuse, or Alpha Orionis, which is also a red 

 star. It differs, too, from the brilliant red star of summer, Antares. 

 Aldebaran has a trace of rose color in its light, while Betelgeuse is of 

 a very deep orange, and Antares may be described as fire-red. These 

 shades of color can easily be detected by the naked eye after a little 

 practice. First compare Aldebaran and Betelgeuse, and glance from 

 each to the brilliant white, or bluish- white, star Rigel in Orion's foot. 



