88 THE NEBULA ABOUT G ORIONIS. 



The utmost care and skill had been devoted to the work, in 

 order to locate the stars justly, and to give all the different de- 

 grees of intensity and convolutions of the light with precision 

 and delicacy. Nevertheless, the first glance which Sir John 

 Herschel obtained of it under the more favorable auspices for 

 observation which he enjoyed ten years afterwards, during his 

 residence at the Cape of Good Hope, sufficed to convince him 

 of the necessity of executing a re-dclineation. This improved 

 drawing, accompanied by a catalogue of the stars situated within 

 the boundaries of the nebulosity, as well as a general descrip- 

 tion, have been embodied in The Results of Astronomical Obser- 

 vations made at the Cape of Good Hope during the Years 1834- 

 38, and published in 1847. 



Other observers, as Derham, Godin, Fouchy, Mairan, Picard, 

 Le Gentil, Messier, De Vico, Lassell, Mitchell, and Lamont, 

 have given us the results of their observations on this interest- 

 ing object. The earlier observations have little value, owing to 

 the deficiency in optical power of the instruments used. As Sir 

 John Herschel's publication embraces nearly every important point 

 connected with the subject which was known at that time, and 

 is founded upon the observations of so many years, made with 

 excellent telescopes, under favorable circumstances, it will be the 

 one principally referred to in this communication ; his nomencla- 

 ture also will be adhered to, as it possesses the advantage of 

 being already well known. 



For the purpose of obtaining a general knowledge of tlie re- 

 gion in which the great nebula of Orion is situated, I com- 

 menced my operations by making a cursory examination of about 

 four square degrees of the heavens in the neighbourhood of 

 Orionis. 



