30 



these minute coloured stars, when informing the Royal 

 Astronomical Society that v was out of the Nebula and in the 

 dark space. They wore seen here and at the Melbourne Ob- 

 servatory. 



No communication, excepting my own, has appeared in refer- 

 ence to 77 having been seen some months later in quite a 

 different portion of the Nebula, after it had left the dark 

 ground of the sky. This is one amongst other changes which 

 has certainly been misconstrued, as very shortly after the 

 account of it reached England a statement appeared in the 

 Quarterly and other journals to the effect that the star t] re- 

 mained in the thick of the nebula — where it was in the Cape 

 drawing — which was not true. 



Owing to a continuation of dry and hot weather, followed 

 by wet and cloudy nights through the month of February and 

 part of March, the present drawing was not completed until 

 the object had reached near the zenith, consequently for 

 checking and completing it, a total reflecting prism by Cook 

 and Sons, with an orthoscopic eye-piece by Ross, was used. 

 With this adoption no sensible difference could occur, as both 

 the size of the field and the definition were much the same ^as 

 in the case of the other drawings. 



The same means for ascertaining the distance of the stars, 

 as adopted in 1871, were again used on the present occasion. 

 The bars of a Cook and Sons Micrometer were traced on the 

 drawing paper so as to just fill the field of the telescope. The 

 value of each bar of the micrometer is sixteen seconds of time. 

 The stars were then pricked down on the paper and the dis- 

 tance of each ascertained by the lines traced from the bar 

 micrometer, which is then taken out of the telescope, and 

 the original eye-piece inserted to finish the drawing. By 

 these means, little or no sensible error can, I apprehend, 

 occur. 



The cardinal points have been omitted in the present draw- 

 ing, and the meridian line only approximately inserted. The 

 telescope used being a refractor, the drawing will require 

 reversion to bring the object into its true position. 



It will be found, on comparison with former drawings, 

 more especially with that of 1871, that although considerable 

 alterations have taken place in the position of the stars sur- 

 rounding 7? Argus, still sufficient similarity exists to allow of 

 their identification, as, for instance, in the case with the four 

 stars convex to 7? (alluded to by Professor Airey). 



The four stars marked 5, 7, t, and |, the small adjacent ones 

 marked 77, p, s, r, x, ^, and the small stars immediately sur- 

 rounding 7?, though agreeing very closely with the drawing 



