June 1, 1886.] 



KNOV^LEDGE 



243 



Fig. 2. — Photogeaph of the Pleiades, by the Brothers Hesrv. 

 Three Exposures, each of one honr. 



THE PLEIADES PHOTOGRAPHED. 



HE accompanying views of the Pleiades en- 

 able us to compare the work of the tele.<!Cope 

 :ind the human eve (6g. 1) with the work 

 of the photographic eye (fig. 2). 



In fig. 1, the star Alcyone is taken a.s 

 the central point from which ascension and 

 declination are measured, the plus sign indi- 

 cating, of course, declination north of Alcyone and increase 

 of right ascension. One of the nebulosities in this map ex- 

 tends from Merope southwards and westwards, and around 

 the Pleiades northwards. The other extends northwards 

 from Pleione. But although M. Wolf, to whom this map is 

 due, indicates this enormous extension of both nebulosities, 

 there is in truth little authority for it. 



In fig. 2, we have the result of photography alone. The 

 nebulosity from INIerope is shown with much less extension 

 than in fig. 1, but with indications of detail such as 

 M. Wolf's drawing does not present. The chief interest of 

 this photogiaphic view, however, resides in the nebulous 

 extension from :Maia, which had never been detected by 

 human eve. 



Fig. 3. — Chart of the Nise Chief Stabs of the 

 Pleiades Cluster. 



Fio-. 3 is added to enable the student to identify the lead- 

 ing stars of the group. All three figures are from M. Flam- 

 marion's Revue (VAstronomie. 



Next month we propose to consider the significance of the 

 nebulosities in the Pleiades, a.s throwing important light on 

 the structure of the stellar universe. An enlarged view of 

 the nebula around Maia will then" be given. 



