ASTRONOMY, PROGRESS OF, IN 1890. 



dromeda. Of course it is true to nature; but 

 when compared with drawings made at the tele- 

 scope, it exhibits scarcely a recognizable feature. 

 The center of the nebula, which is very much 

 elongated, is surrounded with two rings some- 

 what resembling those of Saturn ; and we now 

 know the nature and cause of the dark channels 

 running through it first noticed by Bond. These 

 are UK- dark spaces between the rings, visible 



the stars in its vicinity marred the main feature 

 of the nebula proper. 



Orion Nebula. The photographic extent of 

 this nebula far exceeds that of any other in the 

 heavens, and much interest attaches to it there- 

 from. In the fine photograph of it made by Mr. 

 Common, of England, it appears in many re- 

 spects as visually seen with the telescope. As 

 his design was to "photograph the nebula and not 

 its vicinage, the exposure 

 was limited. The pho- 

 tograph of this nebula by 

 Prof. W. H. Pickering at 

 Wilson's Peak, which in- 

 cludes the surrounding 

 regions, reveals streams 

 of nebulous matter as- 

 tonishing in extent. He 

 says ("Sidereal Messen- 

 ger," January, 1890) : 

 " We have recently con- 

 siderably extended the 

 nebulosity about Theta 

 by giving longer expos- 

 ures and using a quicker 

 lens. The connection 

 with c is now well 

 marked, while the long 

 nebulous streak extend- 

 ing southward from Zeta 

 is broadened and joins c 

 upon the other side, con- 

 necting the sword-handle 

 with the belt. This ex- 

 tension is of much greater 

 area than the other two 

 nebulae combined. Its 

 northern portion as far 

 as 3 30' south declension 

 is fairly conspicuous, and 

 makes an excellent test 

 object, not of the instru- 

 ment or the steadiness, 

 but of the clearness of the 

 air and the blackness of 

 the sky. Owing to recent 

 advances in stellar pho- 

 tography, this matter of 

 sky illumination has as- 

 sumed considerable im- 

 portance, and it is very 

 doubtful if any of the 

 fainter nebulous exten- 

 sions here described can 

 be photographed at any 

 observatory located in or 

 near a large city. This 

 is due, undoubtedly in 



NEBULA IN ANDROMEDA. 



part to the gas, but chiefly 

 to the electric lights 



only photographically. The nebula proper, the 

 rings, the spaces between, and its surroundings 

 are dotted with thousands of stars, as the en- 

 graving clearly shows, though, it must be remem- 

 bered, it, is designed to show details of the nebula 

 itself rather than the stars in its neighborhood, 

 which would have required a much more pro- 

 longed exposure. Prof. Barnard has also success- 

 fully photographed this nebula, or rather its sur- 

 roundings, as the over-exposure (4 h 18 m ) to attain 



which illuminate the 

 slight atmospheric haze and aqueous vapor. A 

 large spiral nebula, which starts from between 

 Omega and Psi, is seen on the plate, passing four 

 degrees north of Zeta, extending to Beta, thence 

 north to Eta, with an outside stream lying nearly 

 north and south, and preceding Beta about four 

 degrees. Another stream, lying nearly east and 

 west, precedes Eta about the same amount. This 

 nebula is about 15 in length by nearly the same 

 breadth, and surrounds a cluster of bright stars, 



