IV. Remarks on the Great Nebula in Orion. In a letter addressed to Prof. G. G. Stokes, Sec. R. S. By W. Lassell, F. R. S

Abstract

I have been so much interested by the perusal of Lord Oxmantown's observations and drawing of the Great Nebula in Orion, published in the present volume of the ‘Transactions,’ that I venture to offer you a few remarks upon them—the more readily, as I may be supposed to be somewhat familiar with that object, though observed with less advantage of optical power. On comparing the present drawing with my own, made with the four-feet equatorial during my late sojourn at Malta, I find that of the 93 new stars in Lord Oxmantown’s list, there are, I believe, only 24 within the more limited area of my drawing. A good many of these have escaped my notice, while, on the other hand, I have detected several which I do not find in the present Catalogue. The following are instances of a few Three stars north-preceding No. 119; four stars about the hypothenuse of the nearly right-angled triangle formed by the stars 47, 52, and 53; two stars in the triangle formed by 30, 32, and 35; a delicate point about 20" from 104, with several others. Some of these I have so repeatedly and certainly seen, that I wonder not to find them here. The explanation of this discrepancy may possibly in some instances be found in variability, but must, I think, be rather sought for in the influence which the state of atmosphere has on such delicate objects, when the highest combinations of light and power are brought to bear upon them. As this is a nebula of n-eat extent, it is possible, and indeed probable, that there may be some snots on which the concentrated attention of any single observer has not been given under the most favourable circumstances. In my own observations &the question of resolvability appeared always an interesting one to settle, and therefore I gave quite as much attention to the detection of stars as to the tracing of the nebula.