68 H. C. RUSSELL. 



I obtained a clear night, and an exposure of eight hours — again 

 with the short camera — which brings out a host of stars and shows 

 the Milky-Way with a brilliance it has never been seen to have 

 before, at the same time the nebula, is more distinctly shewn and 

 larger. After a series of trials, I have succeeded in getting several 

 fine photographs of this object with the Star Camera, which make 

 it eighteen times larger than the one I used last year. I have 

 however been unable to get a continuous exposure of eight hours 

 with this camera, still in Plate 77, taken March 18th 1891, with 

 five hours forty-three minutes exposure on a fine clear night, and 

 in others taken about the same time, we have a marvellous 

 revelation of the details of light and shade presented to us in this 

 object, which have never been seen before in any photograph, or 

 by any telescope. 



Something like the appearance would be produced, if one took 

 a number of tufts of long- fibred wool, and dropped them one 

 after the other on to a black cloth ; as they fell and rolled over 

 one another, they would arrange themselves in curves and lines, 

 through which as one looked down at them, the dark cloth would 

 here and there be seen through tangled wreaths of wool ; and in 

 others the cloth would be wholly hidden by the mass of such lines 

 and curves, which would nevertheless be sufficiently distinct to 

 shew how the mass of white was made up ; but no description 

 could correctly convey the wonderful detail which the photograph 

 reveals ; the general form of this object is the same as in draw- 

 ings, and in the photographs exhibited last session, but there are 

 certain new features which may be indicated. In the first place, 

 there is evidence here that the nebula is much more extended and 

 the spiral structure more decided, and it can be traced even to the 

 details of the fainter branches. Secondly, the nebula covers a 

 much larger area than that of Orion. Thirdly it proves conclusively 

 that a conspicuons part of the nebula which Herschel drew and 

 described in 1838 has entirely disappeared. I pointed this out in 

 1872, but as I then used a telescope inferior in power to HerscheFs, 

 its invisibility to me, was not proof that it was gone. Now the 



