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aspect, and that if all were similarly placed as to the line of sight, a 

 few normal forms would represent the whole. If this is the case, 

 had we a sufficient number of accurate sketches, it is probable that 

 out of the apparent confusion we should succeed in extracting the 

 normal forms. It is also probable that in the nebular systems 

 motion exists. If we see a system with a distinct spiral arrangement, 

 all analogy leads us to conclude that there has been motion, and 

 that if there has been motion that it still continues. The apparent 

 motion is probably very slow, owing to the immense distance of the 

 nebulae ; still there are double stars known to be physically double 

 from their motions, which are probably as distant as some of the 

 nebulae. In certain nebula stars are so peculiarly situated that we 

 can scarcely doubt their connection with the nebular system in 

 which we see them, and some of these stars are as bright as some 

 of the stars known to be physically double ; as bright even as some 

 of the stars which the latest Pulkowa observations have shown to 

 have sensible parallax, and whose distance therefore is approximately 

 known. We have therefore some vague idea, resting on probable 

 evidence, even of the distance of the nearest nebulae. It seems there- 

 fore not unreasonable to expect that measurements perseveringly 

 carried on will detect motion, and that a fulcrum will thus be 

 obtained, by which the powers of analysis may be brought to bear 

 upon the laws which govern these mysterious systems. 



In the northern catalogue of Nebulae, and the same observation 

 no doubt applies to the southern also, there are vast numbers much 

 too faint to be sketched, or measured, with any prospect of advan- 

 tage ; the most powerful instruments we possess, showing in them 

 nothing of an organized structure, but merely a confused mass of 

 nebulosity of varying brightness. The number of nebulae in the 

 northern hemisphere, in which details are well brought out, 

 is not very large, and even in these, a great proportion of the 

 measurements are necessarily rough, and wanting in that precision 

 by which the motion of certain double stars was so soon detected. 

 It is evident therefore that to obtain a true knowledge of the forms 

 of the nebular systems, our sketches must be as numerous as possi- 

 ble ; and to obtain evidence of motion with rough measures, our 

 measures should be very numerous also ; but the northern hemi- 

 sphere presents but a very limited list of suitable objects, therefore 

 it is desirable to take in the southern hemisphere also. 



I have thus, I believe, in part at least, explained the views of 

 those who felt anxious that the southern hemisphere should be exa- 

 mined with a telescope of great power : the first attempt to give 

 practical effect to their wishes was at the meeting of the British 

 Association held at Birmingham in 1849. 



The President of the Association was on that occasion directed to 

 apply to Government to send a telescope of great power, in charge 

 of an experienced observer, to the southern hemisphere. That 

 application was unsuccessful ; the Government, while they acknow- 

 ledged the importance of the proposed object, declined to proceed, from 

 an apprehension of difficulties, through which they did not then see 



