210 Clusters and Nebulae. 



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aperture I can just see the stars; with 6 it is resolvable. 

 The effect of a still greater profusion of light is somewhat to 

 alter its aspect. With twice H/s aperture, though not four times 

 his illuminating power, owing to the Newtonian arrangement 

 being employed instead of the front view, the Earl of Rosse 

 found a greater intermixture of large and small stars, giving 

 a uniform roundish centre of large ones, with a sudden set- 

 off, beyond which were a great number of small ones with a 

 few large ones intermixed ; the outer edges having a tendency 

 to run in rays. 



There can scarcely be a more wonderful sight, of its kind, 

 than this starry globe ; or one that gives a stronger impres- 

 sion how little it is that we know of the true nature of what is 

 surrounding us on every side. That aggregation of several 

 thousands of suns is obviously bound together by some law of 

 inter-dependence, of which we, the attendants of a solitary 

 star, have no idea whatever : they are evidently as it were one 

 family dwelling apart, wholly insulated from the rest of crea- 

 tion, and jointly inhabiting a separate and circumscribed 

 region in the immensity of space. It is impossible to look 

 upon that most beautiful mass of stars, even in its feeble tele- 

 scopic representation, without feeling how little pretension 

 our own system can have to a central or dominant position 

 among the works of God; and how amazing would be its 

 aspect, if we could view it from a point where its proportions 

 to the unaided sight would swell out to those of a globe of 15° 

 or 20° in diameter. We can indeed expand it artificially to 

 that apparent size. A power of 600 or 800 would spread it to 

 that angular extent. But how far would that dim substitute 

 fall short of the magnificent original, with a brightness, even in 

 the gigantic telescopes of Poulkova or Harvard, diminished to 

 6 Vth* of the reality ! And what words could express the splen- 

 dour of the spectacle in the interior of that globe ! " Imagi- 

 nation cannot but picture," as Smyth remarks, " the incon- 

 ceivable brilliance of their visible heavens, to its animated 

 myriads ." It is true that in our total ignorance of the real 

 distance of these clusters from our system, we can form 

 no notion of the amount of their internal compression, but 



* The mode of obtaining this result is as follows : — Assuming a diameter of 

 1J*, as given by H, this will be enlarged to 15° by a power of 600. The area of a 

 15 inch object-glass is 5625 times greater than that of the pupil of the eye, ad- 

 mitting the latter, as usual, to be £th of an inch in diameter, and if no allowance is 

 made for loss of light in the instrument, by so much will the brightness of the 

 telescopic exceed that of the natural image. But, as light diminishes with the 

 square of the distance, at C oo tn of the distance we should hare 360,000 times the 

 light : and this sum divided by 5625 previously obtained, gives 64 times the 

 brightness of the natural object as compared with the telescopic image, even 

 under these very favourable circumstances. With a 6-inch object-glass, the dif- 

 ference would amount to 400 times. 



