Annals of the Astronomical Observatory of Harvard College, Volume 5 |
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Annals of the Astronomical Observatory of Harvard College, Volume 2,Nummer 2 Volledige weergave - 1867 |
Veelvoorkomende woorden en zinsdelen
angle appears Arge Bond Bond's bright brighter catalogue chart clear Coef Comp compared connection contains Continued correction dark Date declination definition determined diagram difference direction distance drawing easily engraving equations error estimated faint fainter field G. P. Bond give given Grades Herschel Lassell less Letter light looked magnitudes March mass mean Name nearly nebula nebulosity noticed observations Orionis position Prec preceding present Principal probably Prof Reading of Scale Reduction referred region relative remarkable right ascension seen Sequence side small stars Struve's Supplement to Zone term tion trace Transit trapezium usual variable VIII visible vision W. C. Bond wire XVII XVIII Zone
Populaire passages
Pagina 171 - ... nevertheless, very essential features in a correct apprehension of its structure, supplying, as they do, what would otherwise appear as breaks of continuity, and assisting materially in the recognition of a principle of regularity pervading the whole structure. Until the law of relation and continuity in the several parts of such an object is entertained in the mind, it must remain an incoherent, confused assemblage of material, having no orderly or connected arrangement. The change from the...
Pagina 170 - Orionis representing its appearance in the twenty-three-foot refractor of the Observatory of Harvard College. The feature to which attention was particularly directed was the spiral structure of the principal masses of light, or, more correctly, the tendency to an arrangement in elongated wisps or whirls, sweeping outward from the bright region of the Trapezium. A disposition of the nebulosity in some localities to radiate from the vicinity of the Trapezium, noticed in the memoir published by Professor...
Pagina 171 - Trapezium, are plainly distinguished as tufts or curled offsets from a prominent wisp of light which extends from its origin, near the Trapezium, across the R. Gentiliana. The general aspect of the greater part of the nebula is therefore that of an assemblage of curved wisps of luminous matter, which, branching outward from a common origin in the bright masses in the vicinity of the Trapezium, sweep towards a southerly direction, on either side of an axis passing through the apex of the Regio Huygeniana,...
Pagina 171 - Messier, in which the original discovery of the spiral arrangement was made. This object had been subjected to a careful examination and description by both the Herschels ; but neither their drawings nor descriptions furnished the slightest intimation of a spiral structure. It deserves particular notice, too, that there was no want of sufficient optical power to exhibit the appearance in question ; for the spirality is seen with perfect distinctness in a refractor of 15 inches aperture, and must...
Pagina 171 - About twenty of these convolutions have been distinctly traced, while others giving a like impression are too faint or too intricate to be subjected to precise description. It may therefore be properly classed among
Pagina 170 - ... of the whirls were thus defined by two independent processes, the nebula being first sketched as a bright object on a dark ground, and, again, its darker openings and channels as dark objects on a white ground. The quarter designated in Herschel's chart * as the Regio Godiniana was first explored. The nebulosity was here resolved into an assemblage of three or four long wisps, interlaced with each other, or crossed by offsets ; these were ultimately traced from a point near the northern margin...
Pagina 171 - Subnebulosa, cannot be resolved into a regular structure, but three or four condensed spots, constituting the most brilliant part of the nebula close on the south-preceding side of the Trapezium, are plainly distinguished as tufts or curled offsets from a prominent wisp of light which extends from its origin, near the Trapezium, across the R. Gentiliana. The general aspect of the greater part of the nebula is therefore that of an assemblage of curved...
Pagina 171 - This object had been subjected to a careful examination and description by both the Herschels, but neither their drawings nor descriptions furnished the slightest intimation of a spiral structure. It deserves particular notice, too, that there was no want of sufficient optical power to exhibit the appearance in question ; for the spirality of 51 Messier is seen with perfect distinctness in a refractor of 15 inches' aperture, and must certainly be within reach of the twenty-foot Herschelian reflectors.
Pagina 171 - Others, which are less curved, originate near the Sinus Gentilii ; these are narrow and somewhat tortuous. It is to be noticed that the initial direction of the wreaths (Nebelstreifen) changes continuously from an angle of position of 330° on the northern margin of the Sinus Magnus, to...
Pagina 171 - ... larger optical power of Lord Rosse's telescope, too plainly not to insure notice ; and the nebula then presented itself under a totally different aspect. Instances of similar revelations, completely at variance with previous conjectures, have indeed so often occurred in the history of astronomical discovery, that the process ought to be regarded as the ordinary rule, rather than as an unusual exception.