522 THE POPULAR SCIENCE MONTHLY. 



Still another curious fact about the Pleiades, is the existence of 

 some rather mysterious nebulous masses in the cluster. In 1859, Tem- 

 ple discovered an extensive nebula, of an oval form, nearly egg-shaped, 

 with the star Merope immersed in one end of it. Subsequent obser- 

 vations showed that this strange phenomenon was variable. Some- 

 times it could not be seen ; at other times it was very plain and large. 

 In Jeaurat's chart of the Pleiades, made in 1779, a vast nebulous mass 

 is represented near the stars Atlas and Pleione. This has since been 

 identified by Goldschmidt as part of a huge, ill-defined nebula, which 

 he thought he could perceive enveloping the whole group of the Ple- 

 iades. Many observers, however, could never see these nebulous 

 masses, and were inclined to doubt their actual existence. Within 

 the past few years astronomical photography, having made astonish- 

 ing progress, has thrown new light upon this mysterious subject. 

 The sensitized plate of the camera, when applied at the focus of a 

 properly-constructed telescope, has proved more effective than the 

 human retina, and has, so to speak, enabled us to see beyond the reach 

 of vision by means of the pictures it makes of objects which escape 

 the eye. In November, 1885, Paul and Prosper Henry turned their 

 great photographing telescope upon the Pleiades, and with it discov- 

 ered a nebula apparently attached to the star Maia. The most pow- 

 erful telescopes in the world had never revealed this to the eye. Yet 

 of its actual existence there can be no question. Their photograph 

 also showed the Merope nebula, although much smaller, and of a dif- 

 ferent form from that represented by its discoverer and others. There 

 evidently yet remains much to be discovered in this singular group, 

 and the mingling of nebulous matter with its stars makes Tennyson's 

 picturesque description of the Pleiades appear all the more life-like : 



" Many a nicfht I saw the Pleiads, rising through the mellow shade 

 Glitter like a swarm of fire-flies tangled in a silver hraidy 



The reader should not expect to be able to see the nebulae in the 

 Pleiades with an opera-glass. I have thought it proper to mention 

 these nebulous objects only in order that he might be in possession of 

 the principal and most curious facts about those interesting stars. 



Orion will next command our attention. You will find the constel- 

 lation in ]\Iap No. 2. 



" Eastward beyond the region of the Ball 

 Stands great Orion; whoso kens not hitn in cloudless night 

 Gleaming aloft, shall cast his eyes in vain 

 To find a brighter sign in all the lieaven." 



To the naked eye, to the opera-glass, and to the telescope, Orion is 

 alike a mine of wonders. This great constellation embraces almost 

 every variety of interesting phenomena that the heavens contain. 

 Here we have the grandest of the nebuLi?, some of the largest and 

 most beautifully-colored stars, star-streams, star-clusters, nebulous stars, 



