

NEBULA, CLUSTERS, ETC. 37 



Herschel. W. : Abstracts of Memoirs — Continued. 



A.D. Vol. P. 



1817 107 326 If the stars of the 5th, 6th, and 7th magnitudes cannot be 



supposed to he gradually of a smaller physical size and 

 brightness than those of the 1st, 2d, and 3d, how much 

 less can a .supposition be admitted that would require that 

 the stars, which, by a long series of gauging powers, have 

 been proved to make their gradual telescopic appearance 

 should also be gradually of a different construction with 

 regard to physical size and brightness from those which 

 we see with the naked eye? 



327 The telescopic breadth of the milky way considerably ex- 

 ceeds the extent whicb, in our maps, is assigned to it. 



328-30 Observations — sweeps — which confirm this. 



330 X.. Concluding Remarks. 



What has been said of the extent and condition of the 

 milky way in my papers on the construction of the heav- 

 ens, with the addition of this attempt to give a more 

 correct idea of its profundity in space, will nearly con- 

 tain all the general knowledge we can ever have of this 

 magnificent collection of stars. 



331 Our sun with all the stars we can see with the eye are 



deeply immersed in the milky waj r , and form a compon- 

 ent part of it. 



1818 108 429 Astronomical observations and experiments, selected for the 



purpose of ascertaining the relative distances of clusters 

 of stars, and of investigating how far the power of our 

 telescopes may be expected to reach into space when directed 

 to ambiguous celestial objects. 

 The method of equalization of star light will show the 

 relative distances of stars ; from this a method was ex- 

 plained in P. T., 1817, by which means the profundity in 

 space of every object consisting of stars can be ascer- 

 tained as far as the light of the telescope suffices. This 

 method may be used to ascertain the profundity of 

 globular and other clusters. 



430 I. Of the distance of globular and other clusters of stars. 

 General principles to guide in such observations. 



431 II. A series of observations of clusters of stars from which 



the order of their profundity in space is determined. 

 431-51 Observations of H. vi, 7, 9, 10, 11, 12, 17, 20, 26, 35, 



38, 41, 63, and of M. 1, 2, 3, 4, 5, 9, 10, 11, 12, 13, 14, 



15, 19, 22, 30, 33, 34, 35, 53, 55, 56, 57, 62, 67, 68, 69, 71, 



72, 74, 75, 77, 79, 80, 92, 97. 

 451 III. Of a method to represent the profundity of celestial 



objects in space by a diagram. 



